Dry regions cover 30% of earth's land surface

2 climate types are commonly recognized

Arid or desert

Semiarid or Steppe

Low latitude deserts

In the vicinities of the tropics of cancer and capricorn

areas where dense dry air sinks back toward the earth's surface

Differs from that of running water in 2 ways

Wind is less capable of picking up and transporting coarse material

Wind is not confined to channels and can spread sediment over large areas

Bedload

Saltation-skipping and bouncing along the surface

About 20-25% of the sand transported in a sandstorm is moved this way

Suspended load

Blankets or mantles of windblown silt

Primary source of the silt is glacial outwash deposits

Extensive deposits occur in China and the central U.S.

Ridges or crested mounds of sand

Often asymmetrically shaped

Windward slope is gently inclined

Leeward slope is steeper and called the slipface

Slow migration of dunes in the direction of wind movement

Barchan

Transverse

Longitudinal

Parabolic

Stardunes

F5 Tornado- up to 315 km/ hour

200 mi/ hour

Oklahoma city- May 3, 1999

wind speeds as high as 312- 318 km/ hr estimated from imaging