Reason 1: The tilt of the earth's axis. The sun's heat reaching the earth in the northern hemisphere is coming in at a shallow angle. It is much less direct than in the summer.
Reason 2: Since it gets colder because of less light in winter, there is a lot of snow. In the northern hemisphere, there is much more land than the southern hemisphere. With such a large amount of snow cover, the light and heat is reflected by the snow back out into space.
Reason 3: The southern hemisphere has a lot of water. During the summer, the heat from the sun causes water to evaporate and create clouds. Clouds are excellent at reflecting radiation. This cloud cover helps to direct the heat back out into space.
But overall, the distance between the Earth and sun is quite insignificant to have much of an effect on global temperatures.
2007-05-03 16:37:19
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answer #1
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answered by Enceladus 5
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The northern hemisphere is tilted away.
When it is tilted away, light from the sun hits at a more oblique angle.
This means the same amount of sunlight gets spread over a larger area of the ground, resulting in less heating.
Also, sunlight has to pass through a greater distance of atmosphere.This allows more sunlight to be scattered away to space before it reaches the ground, causing even more cooling.
The same effects happen in the southern hemisphere, but on opposite months, because when the north pole is tilted away from the Sun, the opposite pole is tilted toward it.
The tilt effect is much greater than the Earth's varying distance from the Sun, because the distance does not really vary that much, so the tilt effects overwhelm the distance effects.
2007-05-03 16:45:25
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answer #2
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answered by campbelp2002 7
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The difference in distance to the sun is insignificant compared to the angle of the sun's rays on the earth. In summer (northern hemisphere), the sun's rays strike more nearly at a right angle to the northern hemisphere, heating the ground more, and causing warmer temperatures. In effect the sun's energy isn't diluted by hitting the earth at a low angle, and spreading out the energy over a large area. During northern hemisphere winter the energy of the sun is spread out over a larger area (because the northern hemisphere is tilted away from the sun), so energy per area is less. Hence, colder temperatures.
2007-05-03 16:33:19
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answer #3
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answered by David A 5
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You're right. Because the northern hemisphere is tilted away from the sun, that is why there is winter in January. That's the only reason I know about.
2007-05-03 16:32:56
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answer #4
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answered by ? 6
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Nothing to do with distance from the sun - the amounts are too tiny.
The tilt of the Earth causes the sun to rise higher in the sky in summer and lower in winter.
it is exactly the same effect on a longer timescale as the difference between the sun in the early morning and the sun at midday.
1. the sun shines through more atmosphere in winter (also ealry and later in the day)
2. the sun's light is more spread out when the sun is lower in the sky - shine a flashlight straight down and then the ground 10 meters in front of you and see the difference in intensity.
3. The hemisphere in summer experiences a longer daylight period (more time to heat up, and less night to cool down), going to extremes at the poles, where they have 6 months daylight in summer and six months night in winter.
2007-05-03 17:45:30
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answer #5
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answered by nick s 6
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If the Earth is 5% closer to the Sun, it gets about 10% more heat. But due to the tilt of the Earth, Iowa gets much less than 90% as much heat in the winter. Still, northern winters are less severe than they would be if the Earth's orbit was circular.
2016-05-20 00:43:52
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answer #6
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answered by Anonymous
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Hi,The Earth's axis of rotation is not perpendicular to the plane of its orbit around the Sun.When the Sun is directly over the Equator,the Earth is not inclined.As the Earth starts to tilt upward the Sun appears to move down away from the Equator until it is directly over the Tropic of Capricorn (23.5degrees south).which is farthest from the Equator.This is when the Northern Hemisphere experience Winter (winter solstice) and the Southern Hemisphere is in Summer. The Earth stops then starts to tilt down over the Equator,while the Sun appears to move north until it is over the Tropic of Cancer.(23.5degrees north) which is farthest from the Equator.
This is what gives us our 4 seasons .One full tilt up followed by one full tilt down. So when the Sun is over the Equator day and night have the same number of hours (Equinox)Which is Spring and Autumn.and when it is over the Tropic of Cancer and over the Tropic of Capricorn we have the summer and winter Solstice.
I hope i have made some sense of this for you. Cheers
2007-05-04 01:42:08
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answer #7
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answered by ROBERT P 7
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The only reason you need is the tilt of the earth. When the earth is tilted away from the sun, then that hemisphere will receieve less light per square meter. Less light also means less energy, so it is colder. . .
2007-05-03 16:33:01
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answer #8
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answered by Walking Man 6
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I hope no teacher asked you to give three reasons. There is only one. It is the tilt, as others have stated. (Declination of the earth's polar axis to the plane of the ecliptic.)
2007-05-07 10:58:37
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answer #9
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answered by Brant 7
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