Itcz and Hadley cell






Droughts are often the result of long-standing anti-cyclones or high pressure systems. The winds move clockwise in the northern hemisphere and are not as intense as low pressure systems. They often move more slowly and cover a wider area and provide for more stable weather.

Warm anti-cyclones often develop when there is warm air in the lower parts of the troposphere in contrast to cold air in the upper part of the troposhere. This then leads to excess pressure.

Droughts also occur with the presence of very dry air masses. These air masses develop when there is a dominance of tropical continental air and an easterly flow as well as a high pressure area. This leads to dry, warm weather conditions.

Droughts develop when these conditions exist for a long time. It obviously affects water supplies and farming. This often leads to a demand for water conservation and economically there will higher food prices as some products fail due to a lack of rainfall. This can often lead to farmers going out of business.

One of the consequences of long-term droughts could be desertification. Vegetation dies as there is less and less moisture available. With less vegetation there is more solar radiation and therefore more heating. Soil fertility decreases with less vegetation and soil gets eroded more easily. All of this will impact the food supplies of the people in the area.

How does land mismanagement lead to desertification?

In drought-stricken areas, land management could increase the


risks of desertification. With more intensive cultivation of crops and the grazing of animals, natural vegetation is cleared. This leads to more erosion on slopes and sediments clogging up streams which already have little water.

Desert ecosystems are very fragile and can be easily upset by simplifying it. The simplification of biomes means that humans direct the energy towards themselves. People eliminate things they do not need. For example, arable farming removes all consumer organisms and crops primary producers. In pastoral farming people retain one single herbivore species and places themselves as sole carnivores.
The simplification of biomes could lead to desertification. This happens less with hunters, gatherers, and with simple shifting agriculture. But it happens a lot with pastoralism and especially with modern arable farming.
The side-effects of this type of farming could lead to the spread of parasites, pests, and disease which desert environments are susceptible to. There is only one single species with most forms of pastoral or arable farming. With greater species diversity there is a more balanced interrelationship between organisms. Man's monoculture leads to a reduction in soil fertility and therefore there is more soil erosion which leads to desertification.