So the Judaean Desert is a ‘Rain Shadow’ Desert. But what is it exactly? So simply said, a rain shadow is a piece of land that has been forced to become a desert. How? because mountains range blocked all plant growing, rainy weather. When you come to visit the Judean Desert from Tel Aviv you can see this in the best possible way. For example when using highway number 1 that connects Tel Aviv to Jerusalem; then continues to the Dead Sea Area. So you start your journey from the Mediterranean Sea (Sea Level); get to Jerusalem that is on top of the Judean Mountains (850 meters approx), and end in the Dead Sea (450m below sea level) which is located in the Judean Desert.
What Makes the Judaean Desert A ‘Rain Shadow’ Desert?
When you come from the west (Tel Aviv) you clearly see that side of the hills and mountains abundant with flora fauna due to the wet weather system that drops rain end even snow sometimes. On the other side of the Judean mountains; immediately when you pass from West Jerusalem to East Jerusalem on route to the Dead Sea; the rain shadow side – all precipitation is blocked. In a rain shadow, it’s warm and dry. on the other side of the Judean mountains, it’s wet and cool (not including the hot summer months, July-August.)
Why Is There a Difference?
When an air mass moves from the Mediterranean Sea (Sea Level) gaining more and more elevation while going up towards the Judean Mountains; that air mass expands and cools. This cool air can not hold moisture as well as warm air. So Cool air forms clouds, which drop rain and very rarely in our case even snow, as it rises up the Judean Mountains. But immediately after it passes over Jerusalem (the peak), this air mass is expected while it starts down the other side, this very steep and fast drop towards the Dead Sea which is located officially at the lowest place on the planet. The air warms up and the clouds dissipate; meaning there is much less rainfall.
So unlike the Negev Desert which is a part of the World Desert Strip. The Judean Desert is a uniquely local phenomenon. In fact, you can say it has its own microclimate. Also, another interesting fact worth mentioning is that the Judean Desert is officially one of the smallest deserts in the world!