arid/semi arid areas- why deserts recieve little amounts of rainfall.

• Desert= an area with less than 25mm of precipitation. they can be cold, temperate or hot.

why some places recieve so little rainfall (causes of aridity)

global circulation

• convection currents in the atmosphere
• deserts lie under the falling limb of a hadley cell which carries warm air but at high pressure this means there is little rainfall. Rain occurs when warm air rises and condenses when it clashes with cold air forming rain, this is away from the desert area

continentality

• if land is far away from the sea then any mositure carried inland by the wind…