arid environment by muhammad fahad ansari 12ieem 14
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MUHAMMAD FAHAD ANSARI 12IEEM 14TRANSCRIPT
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