| The troposphere is the lowest major atmospheric layer, and is located from the
Earth's surface up to the bottom of the stratosphere.
It has decreasing temperature with height (at an average rate of 3.5 degrees F per thousand feet
(6.5 degrees C per kilometer); whereas the stratosphere has either constant or slowly increasing
temperature with height. The troposphere is where all of Earth's weather occurs. The thin layer
that divides the troposphere from the stratosphere is called the "tropopause", located at
an altitude of around 5 miles in the winter, to around 8 miles high in the summer, and as high as 11 or
12 miles in the deep tropics. When you see the top
of a thunderstorm flatten out into an anvil cloud, like
in the illustration above, it is usually because the updrafts in the storm are
"bumping up against" the bottom of the stratosphere.
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