Robert Wilde, age 12, of Salt Lake City, Utah, for his question:
HOW FAR NORTH CAN DESERTS FORM?
This depends on what we mean by a desert. Most of us regard it as a scorching wasteland, too dry for any plant life. Such deserts are limited to regions near the tropics. If we allow a cooler climate, with a few scrubby plants, we find deserts much farther north. If we include dry frozen regions, we find a few patches of desert within the Arctic Circle.
In 1918 geologists came up with an official description of a desert. Its yearly rainfall must be limited to less than 10 inches; and its climate is expected to range from coolish to scorching hot. In the Northern Hemisphere, the scorchers include the great.sandy Sahara and Arabian deserts, which straddle the Tropic of Cancer. The cooler deserts north of the equator include those of Western North America plus another among the lofty ranges north of India.
Our Western desert reaches above Utah into southern Idaho. Across the world, in central Asia, there are cool, dry deserts that reach much farther north than ours. One is the great Gobi Desert, perched on the cold, dry ranges of western China. This and a neighboring desert region cover an area of 200,000 square miles, and the northern border is as far north as our most northern deserts.
West of the Gobi region and reaching farther north is the arid desert of Turkestan. It includes three quarters of a million square miles of western Russia, where it loops around the Caspian Sea. If it were in North America, its northern border would reach up into Canada.
The Turkestan desert is the most northerly of those in cool and temperate regions. But perhaps this is not the whole story. Within the tundra of the Arctic Circle the weather brings snow rather than rain. In some places the yearly snowfall equals much less than 10 inches of rainfall. In this case, perhaps we can claim that deserts frosty deserts can exist up in North Polar regions.
South of the equator, there are scorching deserts in Africa, South America and Australia. The Patagonian Desert reaches down toward the tip of South America.
However, parts of Antarctica get scanty snowfalls and perhaps we can say that frosty deserts also exist in the South Polar region.