Geography Class 9

Desert

A barren landscape receiving less than 20 inches (50 cm) of precipitation per year

Precipitation

Any form of water that falls from the atmosphere to Earth including rain snow sleet or hail

Climate

Long term patterns of weather in a region over many years

Weather

Short term atmospheric conditions at a specific time and place

High Pressure System

A region of sinking air that warms inhibits cloud formation and produces clear dry conditions

Condensation

The process by which water vapor cools and changes into liquid water forming clouds

Rain Shadow

A dry area on the leeward side of a mountain range where moist air has already released its precipitation

Cold Ocean Current

A movement of cold ocean water that reduces evaporation and limits moisture available for rainfall

Marine Desert

A narrow coastal desert formed by cold ocean currents and limited evaporation

Hot and Dry Desert

A desert with extremely low rainfall high daytime temperatures and large temperature swings between day and night

Semi Arid Desert

A desert with slightly more moisture than hot deserts featuring warm summers cool nights and scattered vegetation

Coastal Desert

A desert along a coast influenced by cold currents with low rainfall and frequent fog or dew

Cold Desert

A desert with cold winters low precipitation and temperature extremes often receiving some snowfall

Polar Desert

A type of cold desert in polar regions where air is extremely cold dry and low in precipitation

Weathering

The breakdown of rocks at Earth’s surface through physical or chemical processes

Mechanical Weathering

The physical breakdown of rock without changing its chemical composition often caused by temperature changes

Chemical Weathering

The breakdown of rock through chemical reactions such as those involving water and dissolved minerals

Exfoliation

A mechanical weathering process in which outer rock layers peel or flake off due to expansion and contraction

Thermal Expansion

The process by which materials expand when heated and contract when cooled

Alluvial Fan

A fan shaped deposit of sediments formed where flowing water slows and spreads out

Sand

Rock fragments usually from granite limestone or sandstone measuring about 0.5 millimeters or larger

Dust

Fine particles formed from clay or volcanic materials smaller and softer than sand

Succulent

A plant that stores water in thick fleshy leaves or stems to survive dry conditions

Dormancy

A survival strategy in which plants or animals temporarily stop growth or activity until conditions improve

Nocturnal

Active during the night and resting during the day

Burrowing

Digging into the ground to escape heat predators or extreme conditions

Desertification

The process by which fertile land becomes desert due to drought deforestation or poor land management

Overgrazing

Excessive feeding by livestock that removes vegetation and exposes soil to erosion

Evaporation

The process by which liquid water changes into water vapor

Aridity

A condition of extreme dryness caused by low precipitation and high evaporation rates