Day and Night
- The Double Whammy!
- The tilt of the Earth creates two changes in the amount of insolation. The first is based on the angle and concentration of the rays. The second has to do with the duration of insolation. As we "tip into winter" not only are the rays less direct, but the number of hours of daylight actually decreases. Fewer hours of daylight means less insolation. We get colder because of less direct rays AND also fewer hours of them.
The image below represents a day in January. The width of the light region represents the number of hours of daylight that particular latitude will receive. Notice that the Northern hemisphere is getting less daylight hours than the southern hemisphere.
Where are we and how much are we getting right now?
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Autumnal Equinox Notice the amount of light and dark are equal in both hemispheres. |
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Winter Solstice Winter in the Northern hemisphere Notice the North is getting much less daylight. Above the Arctic circle is in 24 hour darkness. |
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Vernal Equinox Spring in the Northern hemisphere Both hemispheres are again getting the same number of hours of daylight. (It is identical to the Autumnal Equinox.) |
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Summer Solstice Summer in the Northern hemisphere Notice that the North is now getting many hours of daylight and above the Arctic circle is in 24 hour daylight. |
Other views of the earth at this moment
in time:
Earth View
- from the Sun
Earth View
- over NY
Earth View
- close-up of Lodi, NY
Earth
View - World map with live cloud cover
Earth
View - World map with live average surface temperatures
The next section deals with the reflection, scattering, and absorption of insolation.
