Desert Rain and Wind
Rainfall in a desert is not seasonal. Usually there are sudden, violent thunderstorms. There may be several storms in a year or none for several years. The average rainfall each year is not measured on one year' s rainfall, but on the total rainfall in a long period of time.
Deserts often have huge sandstorms and some deserts have snowstorms.
Rain
In a sand desert, rain usually drains away quickly and the landscape changes only slightly.
In a rock desert, rain drains into previously dry gullies or waterways, called wadis. Heavy rain makes the gullies deeper and flash floods can build up, carrying sand, gravel, large rocks and boulders – and piling them up at the end of the wadi. The wadis become muddy lakes with flat rocky areas in between called mesas.
The Australian desert has many of these lakes. They last long enough for shrimps, frogs and wildfowl to breed, before they evaporate. The water in some of the lakes is very salty – perhaps because of salt in the atmosphere, which comes from ocean spray.
When these lakes dry up, clay, silt or sand is left – encrusted with the salt. These areas are known as playa.
Wind
Wind takes the moisture out of soils and living things. This is called dehydration. Sand and dust are moved around by the wind, which also removes organic materials that make the soil fertile. Because plants are scarce in deserts, wind erosion happens more easily.
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