Nature Watch
November 9, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
Well, we’ve got our first taste of it and more is around the corner: snow. Love it or hate it, snow is part of our lives here in the north, so let’s take a moment to think about and appreciate some of its unique properties.
Why is snow white?
Most natural materials absorb some wavelengths of sunlight and reflect others, which in turn gives these materials their color. Snow reflects most of the sunlight—and visible sunlight is white. The complex structure of snow crystals results in countless tiny surfaces from which visible light is reflected.
How big can snowflakes get?
Snowflakes are aggregations of many snow crystals. Most snowflakes are less than one-half inch across. Under certain conditions—usually involving near-freezing temperatures, light winds, and unstable atmospheric conditions—much larger and irregular flakes close to two inches across can form. No routine measure of snowflake dimensions are taken, so the exact answer is not known.
Is it ever too cold to snow?
It can snow even at incredibly cold temperatures as long as there is some source of moisture and some way to lift or cool the air. It is true, however, that most heavy snowfalls occur with relatively warm air temperatures near the ground—typically 15°F or warmer. Warmer air can hold more water vapor, and that vapor is what makes snow.
When is it too warm to snow?
Snow forms when the atmospheric temperature is at or below freezing and there is little moisture in the air. If the ground temperature is at or below freezing, of course the snow will reach the ground. However, snow can still reach the ground when the ground temperature is above freezing if the conditions are just right. In this case, snowflakes will begin to melt as they reach this warmer temperature layer; the melting creates evaporative cooling which cools the air immediately around the snow flake. This cooling retards melting. As a general rule, though, snow will not form if the groud temperature is 41°F or warmer.
Is it true that there is one inch of water in every ten inches of snow that falls?
The water content of snow is quite variable. While many snows that fall at temperatures close to 32°F and snows accompanied by strong winds do contain approximately one inch of water per 10 inches of snowfall, that ratio is not always accurate. Ten inches of fresh snow can contain as little as one-tenth of an inch of water or as much as four inches of water, depending on the snow’s crystal structure, the wind speed, temperature, and other factors.
Why is snow a good insulator?
Fresh, undisturbed snow is composed of a high percentage of air trapped among the lattice structure of the accumulated snow crystals. Since the air can barely move, heat transfer is greatly reduced. Fresh, uncompacted snow typically is 90-95 percent trapped air.
Why do weather forecasters have so much trouble forecasting snow?
Snow forecasting remains one of the more difficult challenges for meteorologists. One reason is that for many of the more intense snows, the heaviest snow amounts fall in surprisingly narrow bands that are on a smaller scale than observing networks and forecast zones. Also, extremely small temperature differences that define the boundary line between rain and snow make huge differences in snow forecasts.
Why does snow crunch when you step on it?
A layer of snow is composed of ice grains with air in between the ice grains. Because the snow layer is mostly empty air space, when you step on a layer of snow you compress that layer—a little or a lot, depending on how old the snow is. As the snow compresses, the ice grains rub against each other. This creates friction or resistance; the colder the temperature, the greater the friction between the grains of ice. The sudden squashing of the snow at lower temperatures produces the familiar creaking or crunching sound. At warmer temperatures—closer to melting—this friction is reduced to the point where the sliding of the grains against each other produces little or no noise. It’s difficult to say at what temperature the snow starts to crunch, but the colder the snow, the louder the crunch.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
Friday, November 9, 2007
Friday, November 2, 2007
Winter Coming
Nature Watch
November 2, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
Chilly fall days give us a warning that winter is coming, and in response plants and animals (including we humans) adjustment accordingly.
The changing of the season also affects the behavior of bodies of water. You may have heard people referring to lakes “turning” this time of year, and wondered what that means.
It’s a twice-yearly phenomenon related to water and air temperature—here’s how it works: In late summer, lake surface waters reach their annual maximum temperatures. Deeper waters are cooler—in many lakes, there is a definite stratification or layering of water temperatures that you would feel if you were swimming on the surface and then dove down deep. The warmest, least dense waters lie on top; water temperature decreases with depth, reaching its minimum temperature at the greatest lake depths.
In the summer, a deep lake will have three layers in the water column: the upper, warmest water (the epilimnion); a thin middle layer, where temperatures rapidly decrease (the thermocline or mesolimnion); and the deepest, coldest water (hypolimnion).
In autumn, cooler air temperatures and diminished hours of sunlight result in a loss of heat from the lake’s upper water layer. As these waters cool, they become more dense and when they reach about 50 degrees F, they sink into the middle layer below, erasing the temperature stratification that had developed during summer.
Eventually, all the lake water reaches a uniform temperature, and surface winds then mix all the water. When the winds are strong and fairly constant in direction for an extended time, they establish a water circulation pattern—as surface waters are blown downwind, waters from below must rise along the upwind shore to replace those waters pushed across the surface. To complete the circuit, the downwind shore surface waters, piled up by the wind, sink to replace the rising bottom waters.
In time, the resulting circulations will completely overturn and mix all the lake’s water—hence “fall turning.” The phenomenon can at times produce a rotten-egg odor, since the deep waters, which are low in oxygen and high in sulphur, rise to the surface and release sulphurous gases into the air. The turnover also mixes atmospheric oxygen into the lake water, replenishing the oxygen in deep waters and allowing fish to return to the depths where many will spend the winter.
Of course, after the fall turning cools the lakewater and as winter approaches, surface waters approach the freezing mark. Unlike most compounds, water reaches its maximum density as a liquid just before becoming a solid. Under normal conditions, freshwater is most dense at 39 degrees F, and ice, being less dense than liquid water, floats. So as lake waters cool, they sink when they reach 39 degrees. Colder water remains above, and is eventually covered with ice.
In the spring, the cycle happens again in reverse. Ice cover melts, and cold surface waters warm until they reach the temperatures of the bottom waters. Winds blowing over the lake again set up a full circulation system; as warming continues, the three water layers again become established, and a full turn of the cycle is complete.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
November 2, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
Chilly fall days give us a warning that winter is coming, and in response plants and animals (including we humans) adjustment accordingly.
The changing of the season also affects the behavior of bodies of water. You may have heard people referring to lakes “turning” this time of year, and wondered what that means.
It’s a twice-yearly phenomenon related to water and air temperature—here’s how it works: In late summer, lake surface waters reach their annual maximum temperatures. Deeper waters are cooler—in many lakes, there is a definite stratification or layering of water temperatures that you would feel if you were swimming on the surface and then dove down deep. The warmest, least dense waters lie on top; water temperature decreases with depth, reaching its minimum temperature at the greatest lake depths.
In the summer, a deep lake will have three layers in the water column: the upper, warmest water (the epilimnion); a thin middle layer, where temperatures rapidly decrease (the thermocline or mesolimnion); and the deepest, coldest water (hypolimnion).
In autumn, cooler air temperatures and diminished hours of sunlight result in a loss of heat from the lake’s upper water layer. As these waters cool, they become more dense and when they reach about 50 degrees F, they sink into the middle layer below, erasing the temperature stratification that had developed during summer.
Eventually, all the lake water reaches a uniform temperature, and surface winds then mix all the water. When the winds are strong and fairly constant in direction for an extended time, they establish a water circulation pattern—as surface waters are blown downwind, waters from below must rise along the upwind shore to replace those waters pushed across the surface. To complete the circuit, the downwind shore surface waters, piled up by the wind, sink to replace the rising bottom waters.
In time, the resulting circulations will completely overturn and mix all the lake’s water—hence “fall turning.” The phenomenon can at times produce a rotten-egg odor, since the deep waters, which are low in oxygen and high in sulphur, rise to the surface and release sulphurous gases into the air. The turnover also mixes atmospheric oxygen into the lake water, replenishing the oxygen in deep waters and allowing fish to return to the depths where many will spend the winter.
Of course, after the fall turning cools the lakewater and as winter approaches, surface waters approach the freezing mark. Unlike most compounds, water reaches its maximum density as a liquid just before becoming a solid. Under normal conditions, freshwater is most dense at 39 degrees F, and ice, being less dense than liquid water, floats. So as lake waters cool, they sink when they reach 39 degrees. Colder water remains above, and is eventually covered with ice.
In the spring, the cycle happens again in reverse. Ice cover melts, and cold surface waters warm until they reach the temperatures of the bottom waters. Winds blowing over the lake again set up a full circulation system; as warming continues, the three water layers again become established, and a full turn of the cycle is complete.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
Friday, October 26, 2007
Indian Summer
Nature Watch
October 26, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
Although we’re now into November, we may still enjoy an occasional warm, dry day in the coming weeks. Of these sorts of days, the early American writer John Bradbury wrote: “The air is perfectly quiescent and all is stillness, as if Nature, after her exertions during the Summer, were now at rest.”
Such a warm spell is often called “Indian Summer,” a term that dates back to the 18th century in the United States. In general, it is defined as any spell of warm, quiet, hazy weather that may occur in October or November. Some people feel that a true Indian Summer can not occur until there has been a hard frost.
Where does the term “Indian Summer” come from? The earliest written usage was a passage in a letter written in 1778 by Frenchman named St. John de Crevecoeur. He wrote:
“Sometimes the rain is followed by an interval of calm and warmth which is called the Indian Summer; its characteristics are a tranquil atmosphere and general smokiness. Up to this epoch the approaches of winter are doubtful; it arrives about the middle of November, although snows and brief freezes often occur long before that date.”
But what do Indians have to do with it? One theory holds that early native Indians chose that time of year as their hunting season. The mild and hazy weather encourages animals to come out, and the haziness of the air might better enable hunters to sneak up on prey.
Another thought is that Indians at that time were known to have set fires to prairie grass, underbrush and woods, which would have added to hazy, smoky conditions. Other possible explanations include: Indians made use of the dry, hazy weather to attack settlers before winter set in; this time was the season of the Indian harvest; or, that the predominant southwest winds that accompanied the Indian Summer period were regarded by the Indians as a favor or blessing.
Yet another hypothesis, but one having nothing to do with Native Americans, suggests that ships at that time crossing the Indian Ocean loaded up their cargo the most during the “Indian Summer,” or fair weather season. Several ships actually had an “I.S.” on their hull at the load level thought safe during the Indian Summer.
Whatever the explanation, these rare warm, still days are indeed a blessing from nature before the rigors of winter set in—so should we happen to have a stretch of Indian Summer, get out and enjoy it!
You might also mark your calendars to get up early and get outside November 17-18 for the peak of the Leonid Meteor Shower. Visible might be as many as 10 meteors per hour and viewing will be best in the pre-dawn hours. The meteors will seem to originate out of the constellation Leo.
It’s not hard to practice phenology; it’s simply the study of changes in plants and animals as they respond to weather, climate, and the seasons. If you’re a gardener, hunter, bird watcher, nature photographer, or a generally outdoorsy person, you can probably also add “phenologist” to your list of titles.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
October 26, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
Although we’re now into November, we may still enjoy an occasional warm, dry day in the coming weeks. Of these sorts of days, the early American writer John Bradbury wrote: “The air is perfectly quiescent and all is stillness, as if Nature, after her exertions during the Summer, were now at rest.”
Such a warm spell is often called “Indian Summer,” a term that dates back to the 18th century in the United States. In general, it is defined as any spell of warm, quiet, hazy weather that may occur in October or November. Some people feel that a true Indian Summer can not occur until there has been a hard frost.
Where does the term “Indian Summer” come from? The earliest written usage was a passage in a letter written in 1778 by Frenchman named St. John de Crevecoeur. He wrote:
“Sometimes the rain is followed by an interval of calm and warmth which is called the Indian Summer; its characteristics are a tranquil atmosphere and general smokiness. Up to this epoch the approaches of winter are doubtful; it arrives about the middle of November, although snows and brief freezes often occur long before that date.”
But what do Indians have to do with it? One theory holds that early native Indians chose that time of year as their hunting season. The mild and hazy weather encourages animals to come out, and the haziness of the air might better enable hunters to sneak up on prey.
Another thought is that Indians at that time were known to have set fires to prairie grass, underbrush and woods, which would have added to hazy, smoky conditions. Other possible explanations include: Indians made use of the dry, hazy weather to attack settlers before winter set in; this time was the season of the Indian harvest; or, that the predominant southwest winds that accompanied the Indian Summer period were regarded by the Indians as a favor or blessing.
Yet another hypothesis, but one having nothing to do with Native Americans, suggests that ships at that time crossing the Indian Ocean loaded up their cargo the most during the “Indian Summer,” or fair weather season. Several ships actually had an “I.S.” on their hull at the load level thought safe during the Indian Summer.
Whatever the explanation, these rare warm, still days are indeed a blessing from nature before the rigors of winter set in—so should we happen to have a stretch of Indian Summer, get out and enjoy it!
You might also mark your calendars to get up early and get outside November 17-18 for the peak of the Leonid Meteor Shower. Visible might be as many as 10 meteors per hour and viewing will be best in the pre-dawn hours. The meteors will seem to originate out of the constellation Leo.
It’s not hard to practice phenology; it’s simply the study of changes in plants and animals as they respond to weather, climate, and the seasons. If you’re a gardener, hunter, bird watcher, nature photographer, or a generally outdoorsy person, you can probably also add “phenologist” to your list of titles.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
Friday, October 19, 2007
Fall is Here
Nature Watch
October 19, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
We continue our march toward winter! One sure sign is that when we step outside mornings and evenings, we can see our warm, moist breath condense in the chilly, drier air.
The same thing happens as plants and the ground itself “exhales” at night. All air contains moisture, which is called water vapor. The moisture in the air close to the ground comes from the soil and the plants; when this air cools at night, the moisture condenses to form water droplets on the grass and plants—what we call dew. When the temperature falls below freezing point, the moisture in the air freezes into ice crystals and settles on grass and plants—this is frost. Unlike dew, frost damages plants because the water inside the cells of a plant freezes and breaks the cells’ walls, resulting in the death of the affected part of that plant.
This cool fall air is still full of birds; many songbirds have already left the region, but you can still see ducks, Canada geese, woodcock, and snipe on the move, migrating south. Start watching for winter visitors arriving from Canada, like the dark-eyed junco and white-throated sparrow.
Another unmistakeable bird you might chance to see this fall is a wild turkey. The largest game bird in North America, turkeys were historically abundant in central and southern Wisconsin, and provided an important food source for Native Americans and early settlers. Wild turkeys were nearly eradicated from the state, but a successful reintroduction program begun in 1976 has led to healthy populations found throughout the southern two-thirds of Wisconsin.
It was thought that turkeys would not be able to survive in the northern part of the state, because long periods of snow cover would keep them from finding food. However, during the winter of 2003-04, 164 turkeys were released onto six sites in Bayfield and Ashland Counties, and due to a combination of the hardiness of this species, plus our recent mild winters, the turkeys have thrived and expanded their population and range in our region.
Out on Lake Superior, anglers have been pulling on their insulated waders and heading out around the mouths of tributary streams and rivers, hoping to catch coho salmon. At this time of year, cohos migrate from the lake and upstream to spawn.
This popular sport fish, sometimes called a silver salmon or sea trout, is not native to the Great Lakes, but was intentionally brought here to help reduce the populations of alewives (also not native) in Great Lakes waters. By the late 1960s, coho were regularly raised in hatcheries and stocked into the Great Lakes, and now for better or worse have become part of the lakes’ ecosystem.
Become a phenologist! Jot down on a wall calendar each day you see or hear geese outside, then note the day they finally all depart. Keep track of the date of the first snowfall, or the first subzero night, then compare those notes from year to year to make your own record of winter’s arrival.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
October 19, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
We continue our march toward winter! One sure sign is that when we step outside mornings and evenings, we can see our warm, moist breath condense in the chilly, drier air.
The same thing happens as plants and the ground itself “exhales” at night. All air contains moisture, which is called water vapor. The moisture in the air close to the ground comes from the soil and the plants; when this air cools at night, the moisture condenses to form water droplets on the grass and plants—what we call dew. When the temperature falls below freezing point, the moisture in the air freezes into ice crystals and settles on grass and plants—this is frost. Unlike dew, frost damages plants because the water inside the cells of a plant freezes and breaks the cells’ walls, resulting in the death of the affected part of that plant.
This cool fall air is still full of birds; many songbirds have already left the region, but you can still see ducks, Canada geese, woodcock, and snipe on the move, migrating south. Start watching for winter visitors arriving from Canada, like the dark-eyed junco and white-throated sparrow.
Another unmistakeable bird you might chance to see this fall is a wild turkey. The largest game bird in North America, turkeys were historically abundant in central and southern Wisconsin, and provided an important food source for Native Americans and early settlers. Wild turkeys were nearly eradicated from the state, but a successful reintroduction program begun in 1976 has led to healthy populations found throughout the southern two-thirds of Wisconsin.
It was thought that turkeys would not be able to survive in the northern part of the state, because long periods of snow cover would keep them from finding food. However, during the winter of 2003-04, 164 turkeys were released onto six sites in Bayfield and Ashland Counties, and due to a combination of the hardiness of this species, plus our recent mild winters, the turkeys have thrived and expanded their population and range in our region.
Out on Lake Superior, anglers have been pulling on their insulated waders and heading out around the mouths of tributary streams and rivers, hoping to catch coho salmon. At this time of year, cohos migrate from the lake and upstream to spawn.
This popular sport fish, sometimes called a silver salmon or sea trout, is not native to the Great Lakes, but was intentionally brought here to help reduce the populations of alewives (also not native) in Great Lakes waters. By the late 1960s, coho were regularly raised in hatcheries and stocked into the Great Lakes, and now for better or worse have become part of the lakes’ ecosystem.
Become a phenologist! Jot down on a wall calendar each day you see or hear geese outside, then note the day they finally all depart. Keep track of the date of the first snowfall, or the first subzero night, then compare those notes from year to year to make your own record of winter’s arrival.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
Friday, October 12, 2007
Fall Happenings
Nature Watch
October 12, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
This is a great time for hiking! Most insects are gone, and most deciduous trees are now bare up here in the north woods, which means that if you’re walking through the woods, you get to see the countour of the landscape better than you would during the summer, when a full canopy of leaves hems in your field of vision.
It’s a great time for the young at heart to jump in leaf piles too. While you’re rolling around in the leaves, you might wonder what ultimately happens to fallen leaves. Unless they’re raked up and removed, leaves will break up and start decomposing into a layer on the forest floor that’s called humus.
Humus comes in two varieties, mor and mull. Mor humus is found in primarily coniferous forests whose floor is covered with a thick carpet of needles and leaves that decompose very slowly. Forces that decompose mor humus include fungi, springtails and mites; bacteria and earthworms are rare.
Mull humus is typical of deciduous forests—aspen, maple, birch, etc. Mull is either neutral or alkaline compared to the acidic mor humus, and the soil it creates tends to be rich and dark. In mull humus, bacteria are high in numbers, as are earthworms, slugs, millipedes, and lots of insect larvae.
On the edge of the forest, or in abandoned fields, you may notice milkweed plants, whose lavender summer flowers have now turned into large, slipper-shaped seed pods. The milkweed plants themselves grow from two to six feet high, and usually have a single, simple stem with opposing, oval-shaped leaves. The top surface of the leaves is smooth, but the bottom surface is hairy.
The plants’ large seed pods have a warty outer skin filled with downy fluff that will carry the seeds on the wind like a parachute. It’s said that this seed-fluff was used by Native Americans to insulate moccasins, and was also used as stuffing in military life jackets during World War II. The dried empty seed pods of the milkweed also were used as Christmas tree decorations by early pioneers.
Cattails are another plant that disperses its seeds in the fall via tiny parachutes on the wind. This wetland plant is very common to Wisconsin’s marshes, ponds, ditches, rivers and lakes. Cattails grow in dense groups, with up to ten-foot-tall sword-like leaves pointing up to the sky with a hearty stalk standing between them. Atop the stalk is the familiar long oval brown spike. Above the spike will appear a yellowish flower between May and July, but by September or October, after the flower has been pollinated, you’ll see the brown flower head pop open and get very fluffy. This means that the seeds are ripe and ready to float through the air in cottonball-like clumps, ready to start new plants.
You’re probably pulling out your cold-weather clothes and packing away the shorts and sandals for the season. Many animals do something similar, growing thicker coats of fur or adding insulation in the form of fat. The snowshoe hare has started to exchange its thin brown summer coat for thick, fluffy white fur that will provide camouflage as well as insulation for the snowy winter. The transformation starts with the ears and feet, and the full makeover takes about 10 weeks. Some people call this animal the “varying hare” because of this seasonal color change.
By the way, have you ever wondered if there is a difference between a rabbit and a hare? They are different: a snowshoe hare looks like a rabbit at first glance, but in general hares have longer ears, very large hind feet, and longer legs made for jumping. Hares are also born with their fur and their eyes open, unlike the rabbit. The snowshoe hare is slightly larger than the cottontail rabbit as well.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
October 12, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
This is a great time for hiking! Most insects are gone, and most deciduous trees are now bare up here in the north woods, which means that if you’re walking through the woods, you get to see the countour of the landscape better than you would during the summer, when a full canopy of leaves hems in your field of vision.
It’s a great time for the young at heart to jump in leaf piles too. While you’re rolling around in the leaves, you might wonder what ultimately happens to fallen leaves. Unless they’re raked up and removed, leaves will break up and start decomposing into a layer on the forest floor that’s called humus.
Humus comes in two varieties, mor and mull. Mor humus is found in primarily coniferous forests whose floor is covered with a thick carpet of needles and leaves that decompose very slowly. Forces that decompose mor humus include fungi, springtails and mites; bacteria and earthworms are rare.
Mull humus is typical of deciduous forests—aspen, maple, birch, etc. Mull is either neutral or alkaline compared to the acidic mor humus, and the soil it creates tends to be rich and dark. In mull humus, bacteria are high in numbers, as are earthworms, slugs, millipedes, and lots of insect larvae.
On the edge of the forest, or in abandoned fields, you may notice milkweed plants, whose lavender summer flowers have now turned into large, slipper-shaped seed pods. The milkweed plants themselves grow from two to six feet high, and usually have a single, simple stem with opposing, oval-shaped leaves. The top surface of the leaves is smooth, but the bottom surface is hairy.
The plants’ large seed pods have a warty outer skin filled with downy fluff that will carry the seeds on the wind like a parachute. It’s said that this seed-fluff was used by Native Americans to insulate moccasins, and was also used as stuffing in military life jackets during World War II. The dried empty seed pods of the milkweed also were used as Christmas tree decorations by early pioneers.
Cattails are another plant that disperses its seeds in the fall via tiny parachutes on the wind. This wetland plant is very common to Wisconsin’s marshes, ponds, ditches, rivers and lakes. Cattails grow in dense groups, with up to ten-foot-tall sword-like leaves pointing up to the sky with a hearty stalk standing between them. Atop the stalk is the familiar long oval brown spike. Above the spike will appear a yellowish flower between May and July, but by September or October, after the flower has been pollinated, you’ll see the brown flower head pop open and get very fluffy. This means that the seeds are ripe and ready to float through the air in cottonball-like clumps, ready to start new plants.
You’re probably pulling out your cold-weather clothes and packing away the shorts and sandals for the season. Many animals do something similar, growing thicker coats of fur or adding insulation in the form of fat. The snowshoe hare has started to exchange its thin brown summer coat for thick, fluffy white fur that will provide camouflage as well as insulation for the snowy winter. The transformation starts with the ears and feet, and the full makeover takes about 10 weeks. Some people call this animal the “varying hare” because of this seasonal color change.
By the way, have you ever wondered if there is a difference between a rabbit and a hare? They are different: a snowshoe hare looks like a rabbit at first glance, but in general hares have longer ears, very large hind feet, and longer legs made for jumping. Hares are also born with their fur and their eyes open, unlike the rabbit. The snowshoe hare is slightly larger than the cottontail rabbit as well.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
Thursday, October 11, 2007
The Autumnal Equinox
Nature Watch
October 11, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
The Autumnal Equinox occurred on September 22nd, officially marking, in astronomical terms, the beginning of autumn. Did you feel the difference? Probably not, but a huge change did occur.
The Autumnal Equinox marks the time when the sun moves south of the equator. We speak of this in terms of the sun, but the sun does not move; the change is actually brought about by the tilting of the earth. If you think of the earth as a person and North America as being on that person’s belly, the earth-person leans back during this time of year and points its belly into the darkness of space, away from the sun. The earth-person reclines further and further back throughout the winter, causing the sun’s daily peak height to be a little lower in the southern sky and the amount of daylight to progressively decrease. When the earth-person has tilted its belly as far as it can away from the sun, the sun is at its lowest point, or nadir. We mark this date with the Winter Solstice, which occurs around December 21st. This is the shortest day of the year and the first day of winter in the Northern Hemisphere.
The Winter Solstice also marks the point at which the earth-person begins tipping forward again. Eventually, the earth-person sits up straight, and its belt (the equator) is level with the sun. This happens around March 21st, the Vernal Equinox, or first day of spring (“vernal” means “spring”). Day and night are of equal length on this day. As the earth-person begins tipping forward and its belly comes closer to the sun, the sun moves north of the equator, the amount of daylight gradually increases, and the sun appears higher in the sky each day. It reaches its peak, or zenith, around June 21st, the Summer Solstice, which is the longest day of the year.
If that was a little tough to follow, maybe it will help to think of it this way. The word “equinox” means “equal night,” referring to the equal duration of light and darkness on the day of an equinox. More simply, equinox = equator. An equinox occurs when the sun crosses the equator, either headed south for the winter (the Autumnal Equinox) or north for the summer (the Vernal Equinox). On the other hand, “solstice” …… well, the word “solstice” does not lend itself to a clever memory trick; it just isn’t the equinox. It may help to know that the origin of the word “solstice” comes from the Latin for “sun stands still.” A solstice occurs when the sun reaches its highest or lowest point, its zenith or its nadir, and it marks the beginning of summer (at its zenith; the Summer Solstice) and the beginning of winter (at its nadir; the Winter Solstice).
Explanations for the cause and effects of the equinox and solstice are entirely scientific, but the occurrence of these changes holds great importance in many religious and cultural contexts. In general, the Autumnal Equinox marks the end of the harvest season and a time to reflect on the year as we light our home fires and approach the darkness of winter.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
October 11, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
The Autumnal Equinox occurred on September 22nd, officially marking, in astronomical terms, the beginning of autumn. Did you feel the difference? Probably not, but a huge change did occur.
The Autumnal Equinox marks the time when the sun moves south of the equator. We speak of this in terms of the sun, but the sun does not move; the change is actually brought about by the tilting of the earth. If you think of the earth as a person and North America as being on that person’s belly, the earth-person leans back during this time of year and points its belly into the darkness of space, away from the sun. The earth-person reclines further and further back throughout the winter, causing the sun’s daily peak height to be a little lower in the southern sky and the amount of daylight to progressively decrease. When the earth-person has tilted its belly as far as it can away from the sun, the sun is at its lowest point, or nadir. We mark this date with the Winter Solstice, which occurs around December 21st. This is the shortest day of the year and the first day of winter in the Northern Hemisphere.
The Winter Solstice also marks the point at which the earth-person begins tipping forward again. Eventually, the earth-person sits up straight, and its belt (the equator) is level with the sun. This happens around March 21st, the Vernal Equinox, or first day of spring (“vernal” means “spring”). Day and night are of equal length on this day. As the earth-person begins tipping forward and its belly comes closer to the sun, the sun moves north of the equator, the amount of daylight gradually increases, and the sun appears higher in the sky each day. It reaches its peak, or zenith, around June 21st, the Summer Solstice, which is the longest day of the year.
If that was a little tough to follow, maybe it will help to think of it this way. The word “equinox” means “equal night,” referring to the equal duration of light and darkness on the day of an equinox. More simply, equinox = equator. An equinox occurs when the sun crosses the equator, either headed south for the winter (the Autumnal Equinox) or north for the summer (the Vernal Equinox). On the other hand, “solstice” …… well, the word “solstice” does not lend itself to a clever memory trick; it just isn’t the equinox. It may help to know that the origin of the word “solstice” comes from the Latin for “sun stands still.” A solstice occurs when the sun reaches its highest or lowest point, its zenith or its nadir, and it marks the beginning of summer (at its zenith; the Summer Solstice) and the beginning of winter (at its nadir; the Winter Solstice).
Explanations for the cause and effects of the equinox and solstice are entirely scientific, but the occurrence of these changes holds great importance in many religious and cultural contexts. In general, the Autumnal Equinox marks the end of the harvest season and a time to reflect on the year as we light our home fires and approach the darkness of winter.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
Friday, October 5, 2007
Autumnal Equinox
Nature Watch
October 5, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
The Autumnal Equinox occurred on September 22, officially marking, in astronomical terms, the beginning of autumn. Did you feel the difference? Probably not, but a huge change did occur.
The Autumnal Equinox marks the time when the sun moves south of the equator. We speak of this in terms of the sun, but the sun does not move; the change is actually brought about by the tilting of the earth. If you think of the earth as a person and North America as being on that person’s belly, the earth-person leans back during this time of year and points its belly into the darkness of space, away from the sun. The earth-person reclines further and further back throughout the winter, causing the sun’s daily peak height to be a little lower in the southern sky and the amount of daylight to progressively decrease. When the earth-person has tilted its belly as far as it can away from the sun, the sun is at its lowest point, or nadir. We mark this date with the Winter Solstice, which occurs around December 21st. This is the shortest day of the year and the first day of winter in the Northern Hemisphere.
The Winter Solstice also marks the point at which the earth-person begins tipping forward again. Eventually, the earth-person sits up straight, and its belt (the equator) is level with the sun. This happens around March 21st, the Vernal Equinox, or first day of spring (“vernal” means “spring”). Day and night are of equal length on this day. As the earth-person begins tipping forward and its belly comes closer to the sun, the sun moves north of the equator, the amount of daylight gradually increases, and the sun appears higher in the sky each day. It reaches its peak, or zenith, around June 21st, the Summer Solstice, which is the longest day of the year.
If that was a little tough to follow, maybe it will help to think of it this way. The word “equinox” means “equal night,” referring to the equal duration of light and darkness on the day of an equinox. More simply, equinox = equator. An equinox occurs when the sun crosses the equator, either headed south for the winter (the Autumnal Equinox) or north for the summer (the Vernal Equinox). On the other hand, “solstice” …… well, the word “solstice” does not lend itself to a clever memory trick; it just isn’t the equinox. It may help to know that the origin of the word “solstice” comes from the Latin for “sun stands still.” A solstice occurs when the sun reaches its highest or lowest point, its zenith or its nadir, and it marks the beginning of summer (at its zenith; the Summer Solstice) and the beginning of winter (at its nadir; the Winter Solstice).
Explanations for the cause and effects of the equinox and solstice are entirely scientific, but the occurrence of these changes holds great importance in many religious and cultural contexts. In general, the Autumnal Equinox marks the end of the harvest season and a time to reflect on the year as we light our home fires and approach the darkness of winter.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
October 5, 2007
By Susan Benson
Director of Education
Cable Natural History Museum
The Autumnal Equinox occurred on September 22, officially marking, in astronomical terms, the beginning of autumn. Did you feel the difference? Probably not, but a huge change did occur.
The Autumnal Equinox marks the time when the sun moves south of the equator. We speak of this in terms of the sun, but the sun does not move; the change is actually brought about by the tilting of the earth. If you think of the earth as a person and North America as being on that person’s belly, the earth-person leans back during this time of year and points its belly into the darkness of space, away from the sun. The earth-person reclines further and further back throughout the winter, causing the sun’s daily peak height to be a little lower in the southern sky and the amount of daylight to progressively decrease. When the earth-person has tilted its belly as far as it can away from the sun, the sun is at its lowest point, or nadir. We mark this date with the Winter Solstice, which occurs around December 21st. This is the shortest day of the year and the first day of winter in the Northern Hemisphere.
The Winter Solstice also marks the point at which the earth-person begins tipping forward again. Eventually, the earth-person sits up straight, and its belt (the equator) is level with the sun. This happens around March 21st, the Vernal Equinox, or first day of spring (“vernal” means “spring”). Day and night are of equal length on this day. As the earth-person begins tipping forward and its belly comes closer to the sun, the sun moves north of the equator, the amount of daylight gradually increases, and the sun appears higher in the sky each day. It reaches its peak, or zenith, around June 21st, the Summer Solstice, which is the longest day of the year.
If that was a little tough to follow, maybe it will help to think of it this way. The word “equinox” means “equal night,” referring to the equal duration of light and darkness on the day of an equinox. More simply, equinox = equator. An equinox occurs when the sun crosses the equator, either headed south for the winter (the Autumnal Equinox) or north for the summer (the Vernal Equinox). On the other hand, “solstice” …… well, the word “solstice” does not lend itself to a clever memory trick; it just isn’t the equinox. It may help to know that the origin of the word “solstice” comes from the Latin for “sun stands still.” A solstice occurs when the sun reaches its highest or lowest point, its zenith or its nadir, and it marks the beginning of summer (at its zenith; the Summer Solstice) and the beginning of winter (at its nadir; the Winter Solstice).
Explanations for the cause and effects of the equinox and solstice are entirely scientific, but the occurrence of these changes holds great importance in many religious and cultural contexts. In general, the Autumnal Equinox marks the end of the harvest season and a time to reflect on the year as we light our home fires and approach the darkness of winter.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 43570 Kavanaugh Street or on the web at www.cablemuseum.org to learn more about exhibits and programs.
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