The rain shadow effect occurs mainly in dry regions that are separated from an ocean by mountains. As a moist wind from the ocean blows over the mountain it loses moisture and becomes cool. The air then descends on the side of the mountain facing the land and becomes warm and dry. This in turn creates a dry area. The North American desert partly developed due to the rain shadow effect.
Cold ocean currents can affect a region’s climate by lowering the mean temperature and increasing the aridity or dryness of costal deserts in tropical places. For example the Atacama Desert in Peru which borders the South Pacific Ocean is one of the driest places in the world.
Climate change also affects the development of deserts. It has changed cool and wet regions into warm and dry regions and also causes changes in the location or extent of the desert. Climate change also affects sea breezes, increasing the cold ocean affect. Below is an image that relates the increase of tempaerature to change in precipitation levels or dryness.
Human Activities
Human Activities also cause deserts
to change or spread. Plant cover protects the topsoil and the land from erosion.
Many industrial human activities like mining and deforestation lead to desertification
and threaten the land by destroying the balance of the ecosystem.
Improper Farming methods such as improper Irrigation can result in salinization, water pollution, and eutrophication. It can also lead to rivers being disconnected from flood plains and inland water habitats, reducing the ground water recharge. In this way irrigation often changes the migratory patterns of fish and opens paths for exotic species. Overgrazing reduces the vegetation cover and exposes the top soil to wind, promoting soil erosion.
This is the Providence Canyon in Georgia State Park.
This canyon was caused by erosion due to overgrazing and
improper farming methods over a hundred years ago.
The effects of erosion are lasting and underlines
the importance of soil conservation.
