However, it's important to note a few things:

* Most of the precipitation is snow, not rain.

* The actual amount of rainfall is likely even lower, as the majority of precipitation is in the form of snow.

* There can be significant variation from year to year and region to region within polar deserts.

Here's why polar deserts are so dry:

* Cold air holds less moisture. The extremely cold temperatures of polar regions mean that the air can hold very little moisture.

* Lack of significant evaporation. The cold temperatures and frozen ground limit the amount of evaporation that can occur.

* Limited access to moisture-laden air. Polar deserts are located far from the major sources of moisture, such as the oceans.

While polar deserts are not as dry as some other deserts, the extremely cold temperatures and lack of precipitation make them very challenging environments for life.