Answer to Question 1
Deserts are defined as regions where annual precipitation is less than 25 centimeters. A desert is recognized as being a dry place, although it can be either hot or cold.
Answer to Question 2
Water is 800 times denser than air. This observation means that the shear stresses exerted by blowing wind are much less than for flowing water. Sediment grains are also easier to move in water than in air because the grains effectively weigh less in water than in air because of the difference in fluid density.
