World Builders™                                                                  Session Three --  Meteorology             

          Latitude and Altitude 

After many thousands of years your planet will become a world with a solid surface.

     diagram of sun hitting house     

     We know that climate tends to get cooler as we move away from the equator toward the poles.

     As the planet curves, the sun's rays cover more ground, and the sun's heat is diluted.  See how the beam spreads over the slanting roof.

     At the equator, the sun's rays meet the planet straight on, like hitting the side of a house. The heat is more concentrated here.

        As the climate changes, the biomes change, too.

You can experience climate change without going on a trip to the north or south.
Temperatures change with changes in altitude.

The temperature of the atmosphere drops three degrees Fahrenheit for every 1000 feet in elevation rise.

This is why people go to the mountains in the summer: they are looking for cooler temperatures.

In this picture below, we see examples of temperature and biome change.

diagram showing elevation/temperature relationship

     We are pretty close to the equator here. Where the ocean meets the land there is heavy rain, and a beautiful tropical rain forest covers the ground.

     Next comes an area where the tropical rain forest blends into the deciduous forest. As we go up the mountain the vegetation types blend into each other, and before too long we are in a typical deciduous forest with trees that we would expect to see farther north.  Because of cooler winters these trees will lose their leaves in the fall.  The cooling air releases rain as it rises.

     As the elevation continues to rise, the deciduous forest gives way to an evergreen coniferous forest. Here we find trees and bushes that we would normally see much farther north.  These trees gradually become shorter and are spaced farther apart as the forest gives way to a grassy alpine biome. Here marmots whistle among the grasses and wild flowers.

     Eventually, grass gives way to rocks, stones, and snow. The wind is cold up here, and we are feeling the lack of oxygen in the thin air.  We stop to pant after climbing only a few steps.

     At 20,000 feet we are at what climbers call the Death Zone because brain cells are beginning to die from lack of oxygen in the air.  They can survive for a few hours but should not stay here long without bringing and using oxygen cylinders and a breathing mask.

     I hope that the people in the balloon have some oxygen with them, or else are planning to come down very, very soon. They could easily die up there because there is not enough oxygen in this thinning atmosphere for them.

     It is because of this change of temperature with altitude that high mountains are snow-capped even at the equator.

     If your are curious about breathing at high altitudes, check this page to see how air pressure varies with altitude.  A lung-full of air at 20,000 feet does

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Header from NASA Earth From Space
© Elizabeth Anne Viau, 1999. All rights reserved. This material may be used freely for instructional purposes but not sold for a price beyond the cost of reproduction. Please inform the author if you use it at