Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to CuriousKidsUS@theconversation.com.

How hot does it get in the desert? – Henry, age 5, South Bend, Indiana

How hot does it get in the desert? – Henry, age 5, South Bend, Indiana

When you think of a desert, you probably imagine giant waves of sand dunes beneath a blazing Sun. You’d be picturing a hot desert, like the Sahara in Africa.

Some of the most scorching temperatures recorded on Earth have been in deserts. The hottest air temperature on the Earth’s surface was 134 degrees Fahrenheit (56.7 degrees Celsius) in Death Valley, California. The highest ground temperature was 177.4 F (80.8 C) in the Lute Desert in Iran.

For comparison, a very hot bath is around 110 F (43 C). So these temperatures are way beyond anything safe for your skin.

What makes some deserts so broiling hot, and why do they exist in the first place? It has to do with how Earth’s atmosphere moves around our planet and interacts with what’s on the ground.

Climate scientists like me define a desert not by temperature but by how much precipitation it gets – any form of water falling from the sky, whether rain, snow or hail. If an area receives less than 10 inches (250 millimeters) of precipitation a year, it is officially a desert.

There’s nothing in this definition about being hot. In fact, there are cold deserts, too. The biggest desert on Earth is Antarctica, where the average winter temperature can be as low as -75 F (-60 C) in the interior highlands.

Antarctica counts as a desert because it rarely snows there. It’s covered by a large ice sheet that’s the result of tiny amounts of snow accumulating over tens of........

© The Conversation