What IS a Desert?

What IS a Desert?

The dictionary says that a desert is " a dry, often sandy region of little rainfall, extreme temperatures, and sparse vegetation. "

Whew! What does that mean?????

Defining a desert is tricky. You see, scientists don't have just one definition. In fact, there are many definitions. Part of the problem is that each desert is unique. So, the very thing that makes deserts fun to study also makes them hard to define!

Let's look closely at the dictionary definition and see if we can figure it out!

a dry, often sandy region of little rainfall
- This tells us that deserts are dry because they have very little rainfall. The fact is, deserts can only be true deserts if they get 10 inches of rainfall or less in a year. That's not very much!
- We often think of deserts as being full of sand. In fact, the United States Geological Survey says that only 20% of the Earth's deserts is covered with sand. That means most deserts are NOT covered in sand. Most deserts are covered with loose gravel and pebbles!
- Compare the amount of precipitation each year in a desert with other U.S. cities. Remember these are averages. That means that the actual amount of precipitation could be higher or lower.

Seattle, WA = 36.2 in. (92 cm)

Miami, FL = 58 in. (147)

Atlanta, GA = 49 in. (124 cm)

Houston, TX = 45 in. (114 cm)

Boston, MA = 44 in. (112 cm)

New York, NY = 40.3 in. (102 cm)

Washington, DC = 39 in. (99 cm)

Chicago, IL= 34.5 in. (88 cm)

San Francisco, CA = 19.5 in. (50 cm)

extreme temperatures

Deserts are known for having very high and very low temperatures. In fact, the hottest deserts can have ground temperatures over 176°F (80°C). These high temperatures are daytime temperatures. At night, because there are no clouds to trap the heat, the temperature drops rapidly!
Not all deserts have high temperatures. Some of the world's deserts are called cold deserts. The water (precipitation) in these deserts comes from snow instead of rain.
You will learn more about the weather of the deserts in Desert Weather and Location, Location, Location!

sparse vegetation

In the desert there is not much vegetation (plant life). The plants that live there do not grow too close together. They are scattered and separated because there isn't a lot of water to share.
The plants that grow in the desert are able to grow there because they have adapted to the dry weather and extreme temperatures. Without these adaptations, plants would die quickly.
You will learn more about the adaptations of desert plants and animals in Desert Plants and Desert Animals!

Desert Journal #1

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Have fun!!!

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