A Desert vs a Tundra

Like all science fields, there have been arguments on what a particular word really means. In the example below from the USGS Ask-a-Geologist website, the question comes up: what is a desert? Would the Antarctic qualify? Does a desert have to be hot and sandy?

Q:

Hello!
I'm having an argument with a friend;
What is the largest desert? The Sahara or Antarctica?
Can Antarctica be considered a desert or a tundra?
What is the difference between a desert and a tundra?
Thank You,
Ashlee C.

A:

Hi, Ashlee,
Here's the dictionary.com definition of a Desert :
–noun
1. a region so arid because of little rainfall that it supports only sparse and widely spaced vegetation or no vegetation at all: The Sahara is a vast sandy desert.
2. any area in which few forms of life can exist because of lack of water, permanent frost, or absence of soil.
3. an area of the ocean in which it is believed no marine life exists.
4. (formerly) any unsettled area between the Mississippi and the Rocky Mountains thought to be unsuitable for human habitation.
5. any place lacking in something: The town was a cultural desert.

Here's the definition of a Tundra:
–noun
one of the vast, nearly level, treeless plains of the arctic regions of Europe, Asia, and North America.

Some Additional Information:
The Sahara covers about 8.6 million square kilometers; I have spent time there and it is pretty huge, but not a contiguous sand-dune desert like the smaller Empty Quarter in the Arabian Peninsula. You can at least drive across the Sahara and have a chance of getting to the other side.

Antarctica covers about 20 million square kilometers - quite a bit bigger.

From the definitions above, Antarctica is a Desert, but not a Tundra. The Sahara is a Desert, but not a Tundra. Antarctica is more than twice as big as the Sahara.

I hope this settles your argument.

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