Grade 11 Geography: The Atmosphere, Global Circulation, and Droughts

Essential vocabulary covering Earth's energy balance, global atmospheric circulation systems, wind phenomena, and drought types from Grade 11 Geography.

Insolation

The incoming solar energy that reaches the Earth's surface.

Isobars

Lines on a map joining places with equal atmospheric pressure.

Intertropical Convergence Zone (ITCZ)

The low-pressure zone between the tropics where trade winds from the subtropical high-pressure belts converge.

Geostrophic wind

A wind that blows parallel to the isobars when the pressure gradient force and the Coriolis force are balanced.

Air mass

A large body of air extending over thousands of square kilometres with relatively similar temperature and humidity characteristics.

Monsoon winds

Seasonal reversals of atmospheric pressure and winds, along with their accompanying rainfall.

Föhn

Any dry, hot wind that starts from a mountainous area, characterized by a rapid temperature increase of about $1\,^\circ\text{C}$ for every $100\,\text{m}$ descent and a drop in relative humidity.

El Niño

The warming of the sea surface in the tropical eastern Pacific Ocean that causes the normal air and sea water circulation patterns to reverse.

Hydrological drought

A drought that occurs when water reserves fall below an established average, even during periods of average or above average precipitation if water usage and demand are high.

Desertification

A process of land degradation in mainly arid, semi-arid, and sub-humid dry areas that involves turning formerly productive land into desert.