Deserts

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Deserts & Winds

Ch 13:

Today:

“We don’t survive the desert,

we live here”

- Pima Indian

Deserts: where & why

1)

Deserts & 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 & why

Deserts & winds

What causes deserts?

air pressure

wind

Important factors:

Global distribution of

rainfall

evaporation

Relationship between

www.weatherchannel.com

1) Deserts: where & why

Deserts & winds

1) Deserts: where & why

Deserts & winds

Low-latitude deserts

Tropic of Cancer

Tropic of Capricorn

(recall: “latitude” = east-west line on the globe)

Equator:

hot air

rises to 15-20 km

low pressure belt

In contrast….

1) Deserts: where & why

Deserts & winds

1) Deserts: where & why

Deserts & winds

1) Deserts: where & why

Deserts & winds

1) Deserts: where & why

Deserts & winds

Middle-latitude deserts

exist in rain shadows.

Basin and range

2)

Deserts & winds

Basin and range

mountainous desert landscape

2) Basin and range

Deserts & winds

Basin and range

mountainous desert landscape

Wind erosion/ deposits

3)

Deserts & winds

Wind erosion: Important in arid environments

Example: Types of sand dunes:

Sand dune shape depends on:

Flat or hilly?

How much sand?

Winds steady or intermittent?

Wind direction constant?

Vegetation present?