geography 3.1-3.5

weather

The current state of the atmosphere

Atmosphere

Layers of gases, such as nitrogen, oxygen and carbon dioxide surrounding the Earth

Troposphere

Lowest layer of the atmosphere; the top is located between 6 and 17 kilometres from the Earth's surface.

Temperature

Objective measurement of hot or cold conditions

Precipitation

Water, in any chemical state, that falls from the atmosphere; including, drizzle, rain, snow and hail.

Wind

The movement of air through the atmosphere.

Isotherm

Line in a map that shows equal temperature

Evaporation

The change from a liquid to a gaseous chemical state.

Transpiration

Water that evaporates from vegetation

Condensate

The change from a gaseous to a liquid chemical state.

Atmospheric pressure

Pressure, or weight, of the air in the atmosphere

Isobars

Lines in a map that show equal atmospheric pressure

climate

The average weather over an extended period.

Climate graph

A graph which shows average temperature and precipitation throughout the year

Maritime effect

Places close to the North Sea experience this effect: it is cooler in the summer and warmer in the winter

Sea current

Movement of sea water

Warm front

Edge of a warm air mass facing a cold front.

Cold front

Edge of a cool air mass facing a warm front.

Frontal rainfall

Rainfall caused by the meeting of a warm and cold front.

Mediterranean climate

Climate zone with moderate temperatures and a dry summer

Maritime climate

Climate zone with moderate temperatures and precipitation throughout the year.

Continental climate

Warm summer and cold winter, precipitation throughout the year

Climate zones

Divisions of the Earth's climate based on average temperature and precipitation.

Tree line

Boundary along altitude or latitude above which no trees grow.

Snow line

Boundary along altitude or latitude above which snow persists all year round.

Altitude

Height of the Earth's surface.

Orographic rainfall

Rainfall caused by air that is pushed up by a mountain ridge.

Windward side

Upwind. The side from where wind is coming; the wet side of a mountain range.

Leeward side

Downwind. The side to where wind is blowing; the dry side of a mountain range.

Rain shadow

The area that receives little rainfall on the leeward side of a mountain.

Tropic of Cancer

Northern boundary of the tropics located at 23.4° N.

Tropic of Capricorn

Southern boundary of the tropics located at 23.4° S.

Subtropics

Zone which bounds the tropics.

Tropical rainforest climate

Climate zone with high temperatures and precipitation throughout the year.

Savannah climate

Climate zone with high temperatures and a specific dry period.

Monsoon climate

Climate zone with high temperatures and a specific dry period and also very high precipitation events during the wet season

Convectional rainfall

Precipitation caused by incoming solar radiation.

Hadley cell

Tropical atmospheric circulation.

Trade winds

Prevailing winds in the tropics, blowing from east to west.

Intertropical convergence zone (ITCZ)

Area where the northern and southern trade winds come together, causing rising air and thunderstorms.

Monsoon

Seasonal weather changes in precipitation due to the movement of the ITCZ, and convectional rainfall.

Sea breeze

Wind coming from the sea.

Land breeze

Wind coming from the land.

Arid

Dry

Desert climate

Climate zone with very little to no precipitation and high evaporation.

Steppe climate

Climate zone with some precipitation during the wet season, nearly balanced with evaporation rate.

Subtropic maximum

Area of high atmospheric pressure located in the subtropics; the air mass descends.

Polar maximum

Area of high atmospheric pressure located in the polar regions; the air mass descends.

Subpolar minimum

Area of low atmospheric pressure located in the middle latitudes; the air mass rises.

Prevailing wind direction

Most common wind direction.

Westerlies

Most common wind direction in the middle latitudes; a wind that blows from west to east.