DIRECTIONS: Seven deserts, on five continents, that have nothing to do with each other. Fill in each latitude, then look down the column.
the dashed lines are 30° north and 30° south
#
Desert
Which continent
Roughly what latitude?
1.
Sahara
2.
Arabian
3.
Thar
4.
Chihuahuan
5.
Kalahari
6.
Atacama
7.
Great Victoria
The Same Loop, Six Thousand Miles Across
The Shape of the World · Page 2 of 3
DIRECTIONS: Why do deserts line up? Read, then answer.
Air over the equator is heated hardest, so it rises. Rising air cools and
cannot hold its water, so it rains: that is why rainforests are on the equator. The dried-out air travels away high
up and sinks at about thirty degrees. Sinking air warms and takes up water instead of giving it. Dry air on
dry ground is a desert.
Say why the rainforests and the deserts are both explained by the same loop, in opposite ways.
The deserts appear at about thirty degrees BOTH north and south. Say what that tells you about the loop.
A desert is usually explained as "somewhere it does not rain". Using this page, give the better explanation of why it does not.
Where It Does Not Work
The Shape of the World · Page 3 of 3
DIRECTIONS: Where the rule bends.
The Gobi (45°N) is too far inside Asia for wet air to reach. The
Atacama (24°S), the driest place on earth, sits behind mountains that wring the air out first.
Antarctica is a desert too: almost nothing falls there.
The Gobi and Antarctica are both deserts and neither is at thirty degrees. Say what all deserts really have in common, given that latitude is not it.
Does the Gobi disprove the thirty-degree pattern? Say what a good explanation is allowed to leave out.