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Name: Jordan
Status: Student
Age: 6
Location: N/A
Country: N/A
Date: N/A 


Question:
Why does the earth has ice at the top and bottom all the time, but not over the rest of the earth? - Jordan



Replies:
Jordan,

Areas where it is cold most of the time, like the poles, the tops of high mountains, and places like Greenland get snowfall most of the year and have temperatures below freezing most of the year. The snow compresses over time and becomes ice at the higher elevations. It is just plain very cold at the poles most of the year, so even sea water stays frozen at the North pole, and the snow and ice do not melt on Antarctica. The North pole has been a bit warmer the past 15 years, so the ice has thinned there to about half of what it was 25 years ago.

David R. Cook
Atmospheric Section
Environmental Research Division
Argonne National Laboratory


As the earth circles the sun, the line connecting the centers of each reaches only the tropic of cancer in the northern hemisphere and the tropic of Capricorn in the southern hemisphere. If you can find a globe, you will see these latitude lines marked.

Then if you take a flashlight and stand about 10 or 20 feet away from the globe and direct the flashlight's beam at either of these latitude lines, you will see that neither the North or South pole gets much sunlight in either winter [for us] when the sun is at the tropic of Capricorn, or at the tropic of cancer in summer [for us]. Things are just reversed in the southern hemisphere. Because there is such sunlight reaching the poles and that sunlight is at a low angle relative to "straight up", the zenith, neither pole is able to receive enough solar energy to warm up very much.

Vince Calder



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