Atmosphere

What is rainfall in Africa affected by?

Global Circulation of the atmosphere

Explain the climate in mali

• Mali’s rainy season is normally in May

• Its part of the ITCZ

• It has a very short rainy season

What is the ICTZ? (simple as possible)

• Between two cell boundaries (Hadley, Ferrel, Polar)

• Low pressure air rises

• Air currents converge

• Form huge cumulonimbus clouds by water vapour

• This is the Inter-Tropical Convergence Zone

How does the Hadley cell work in africa?

• N and W africa - land is warmer than surrounding seas

• Air warms - expands - rises

• low pressure area forms (over mali and S sahara)

• over gulf of guinea (which is the sea) , area is cooler and denser

• high pressure area

• sea is cooler than land

• wind blow high - low pressure

• towards W africa and S sahara from gulf of guinea

• known as trade winds

• 2 hadley cells

• one brings rain , other in area of high pressure (med and atlantic sea)

• trade winds draw the high pressure in med and atlantic to the area of low pressure over the land (mali and S sahara)

• the two trade winds converge

• rise as they meet

• cool - condense - become heavy rain