Meteorological drought is the level of dryness within a certain area, when it receives less than its usual amount of precipitation and is the most significant cause if drought globally. This particular type of drought is caused by changes in the general weather patterns of an area.
Some areas which are in drought have more precipitation than those that are not, however it depends on how much precipitation is normal for that area.
An area's climate is controlled by the atmospheric and oceanic circulation, therefore slight changes in these can have significant impacts. Global warming is causing the ocean and atmospheres temperatures to change which affects the heat distribution. Climate change is having a large impact on these processes, already causing more severe and frequent drought in certain places.
Jet streams also have an impact on weather systems, for example low pressure systems causing precipitation, being changed from their usual path. So, this affects regions that rely on rainy seasons. The paths of jet streams can be unreliable, therefore this can happen at any time.
Hydrological drought is the impact of low precipitation levels on a hydrological (water) system, for example, a river basin. This has the same cause os a meteorological drought, however its effects are not as readily obvious.
Despite the fact that the surface effects may not be as obvious at first, its impacts on ground water and reservoir levels will take longer to become noticeable.
As less water enters the soil due to a short supply of water from precipitation, caused by meteorological drought, surface water becomes increasingly inaccessible as levels plummet. This in turn leads to groundwater and reservoirs being too heavily relied on.
The effect drought has on crops
Dams are built, Usually on rivers, to work as a flood defence, and create reservoirs to store water that is in turn used for industrial, agricultural and recreational use. However, because this slows the flow of water into rivers it can cause drops in water levels downstream which can leave areas in drought.
Deforestation can also lead to drought. When trees and removed from the rainforest, this results in less carbon dioxide being absorbed from the atmosphere, which leads to an increase in the global greenhouse effect. This then causes climate change which has an impact on the atmospheric and oceanic cirulation.
Agriculture can be impacted by drought which results in crop failures, lower yields and loss of livestock. Additionally, it can also contribute to drought as water is removed from other areas to irrigate agriculture or it is pumped from groundwater and rivers. This decreases water supplies and therefore contributes to and can worsen the effects of drought.