Hot Arid and Semi-arid Environments

MUHAMMAD FAHAD ANSARI 12IEEM 14

Hot Arid and Semi-arid Environments

CLASSIFICATION AND DISTRIBUTION OF HOT ARID AND SEMI ARID ZONES

Definitions

Simple oneWhat is a desert (arid area)?

• <250mm precipitation per year(Semi arid area = 250 – 500 mm per year)

More advanced……

WHAT IS ARIDITY?

Ratio of average precipitation (P) to potential evapotranspiration (PET*) = aridity index

Arid areas: <0.20Semi-arid areas 0.20 -0.50

Koppen's classification

*See page 134 for def of pet

AridSemi-arid

Ch 13: Deserts & WindsCh 13: Deserts & WindsToday:Today:

“We don’t survive the desert, we live here” - Pima Indian

“We don’t survive the desert, we live here” - Pima Indian

1) Deserts: where & whyDeserts & winds

Earth’s dry regions: 30% of all land

2 climate types of dry regions:

desert (arid)

steppe (semi-arid, surrounds deserts)

Question: how much rain do we get in Tempe every year?

1) Deserts: where & whyDeserts & winds

What causes deserts?

air pressure wind

Important factors:

Global distribution of

rainfall evaporation

Relationship between

www.weatherchannel.com

1) Deserts: where & whyDeserts & winds