|MadSci Network: Earth Sciences|
Question: Why is Antarctica not considered the largest desert in the world? From: john Grade: 4-6 City: Liberty Township, State/Prov.: OH Country: USA Area: Earth Sciences Message ID Number: 1001896997.Es We are studying about biomes in science. By definition Antarctica is classsified a desert because of its low percipation. It is much larger than the Sahare Desert. I asked my science teacher this question and he did not know the answer. I have been trying to find out why also, but no where have Ihave been unalbe to find where it explains the the Sahara desert being the largest "hot desert" and Antarctica being really the largest desert. Can you explain this to me? Dear John, You are quite correct to point out that Antarctica is a desert. It is what is known as a cold desert, which is probably why you find that it is not classified along with hot deserts like the Sahara. A hot desert is defined by geographers as a region where the rate of evaporation exceeds precipitation, and where precipitation is below 254 mm per year. In a cold desert, by contrast, there is little evaporation, so low precipitation alone determines its status as a desert. In Antarctica precipitation is less in the interior of the continent than along the coasts. The reason is that coastal areas are more open to the influence of cyclones. In the interior of Antarctica precipitation is as low as 50 mm per year, while in coastal regions it can be as high as 250 mm per year. Thus even coastal precipitation is usually within the range that we would consider to be a desert. The entire continent is, therefore, a vast cold desert. It is, as you rightly say, larger than the Sahara (Antarctica is about 14.2 million square kilometres in size, and the Sahara is just over 9 million square kilometres). As you rightly point out, Antarctica is clearly the largest desert on Earth. The reason you do not often see it listed along with hot deserts is mainly, I suspect, just that people think of deserts as hot. Best wishes, David Scarboro
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