Deserts

Deserts

Deserts formation
1. Rainshadow
  1. Evaporation of water makes air humid
    1. Warm humid air is forced up into the mountains
      1. As the warm humid air rises over the mountains condensation occurs and cloud forms
        Once it is cold enough precipitation falls over the mountain
        Dry air sinks. It is no longer humid as precipitation has occurred
2. Hadley Cell
Desertification
1. Causes
  1. Overgrazing
    1. Overgrazing by cattle, sheep and goats reduces vegetation and leaves the soil exposed
      1. Without vegetation there is nothing to hold the soil together and blows away
  2. Drought
    1. A long period without rainfall, causes crops to die, lack of food, may have to move to find food
  3. The climate is getting drier. On average, it rains less now than it did 50yrs ago
    1. There are fewer trees than there used to be. People chop them down for firewood
  4. Overcultivation
    1. Overcultivation of crops uses up the nutrients in the soil, so yields fall. Eventually, nothing will grow
      1. People have many children, so the population is growing quickly. They need more food and fuel
2. Solutions
  1. Education and national/international negotiations
    1. Raising awareness of the issue to educate others and encourage actions that would reduce the problems caused by desertification
  2. Terracing
    1. Man-Made steps are created on slopes to stop surface run off
  3. Plant trees
    1. This is to create breaks in the wind and protect the land underneath. Ut stabilises the soil, protects it from excessive sunshine and strong winds
3. Effects
  1. Starvation
    1. People and cattle die of starvation
  2. Food Loss
    1. The soil is not suited for growing food; therefore the amount of food being made will decline. If the population is growing, this will cause economic problems and starvation
  3. Loss of Water
    1. Without trees and vegetation occasional flash floods carry the soil away leading to downstream flooding. The surface water is then rapidly lost through evaporation and rivers and lakes disappear. The evaporation means a loss of water as well as a loss of soil displaced there
  4. Famine
    1. Places that have war and poverty are most likely to have famine occur. Drought and poor land management contribute to famine
  5. Soil becomes less usable
    1. The soil can be blown away by wind or washed away by rain. Nutrients in the soil can be removed by wind or water. Salt can build up in the soil which makes it harder for plant growth
Types of Deserts
1. Rainshadow
  1. Precipitation happens on one side of the mountain causing the air to lose it's moisture
    1. Example: Atacama Desert Located in South America, Chile behind the Andes Mountain
2. Inland deserts
  1. Southeast monsoon bring precipitation on the Himalayas
  2. Northeast monsoon brings dry weather
  3. Monsoon desert are seasonal winds
    1. Example: Thar deserts
3. Coastal Desert
  1. Cold ocean currents near the coast cools the air
    1. This causes the air not to rise therefore there's no precipitation
  2. Mist or fog appears because of the cold air
  3. Example: Namib Desert, coastline in the countries of South Africa, Namibia, and Angola

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