Different Weathers: The Effects of Ascending and Descending Air

Chapter 11

Pages 65-71

Definitions

Weather- condition of the atmosphere over a short time

Climate- average condition of the atmosphere over a long time

Air Masses and Fronts

Air mass- large body of airFront- boundary between two air masses

Warm front- where warm air approaches coldCold front- where cold air approaches warm

Ireland and Fronts

Ireland affected by Polar FrontCold air meets warm airWarm air invades section of cold airWarm air is light- rises- low pressure, called a

depression

Develop over Atlantic and move over Ireland

Weather: wet, windy

Depressions and Anticyclones

Occur over mid latitudesDepression

Low pressureOval shapePressure lowest in the centre

AnticycloneHigh pressureOval shapePressure highest in middle

A Depression on a weather map.

Isobars – lines joining points of equal pressure

Isohyets – Lines joining points of equal rainfall

Isotherms – lines joining points of equal temperature

Isohels – equal sunshine

Weather During a Depression

DepressionWeather

Cloudy Wet Windy

•Air Rises•Cools•Condenses- clouds

•Air Rises•Condenses•Falls as rain

•Isobars tightly packed•Blows towards middle

Depression Anticyclone

Anticyclones

Weather During an Anticyclone

Anticyclone Weather

CALM CLEAR DRY

•Isobars widely spread•Winds blows outwards

•Air descends•Warms•Absorbs water

•No condensation•No rain

Temperatures

Summer- Hot

Winter- Cold

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2008 Junior Cert – Higher Question

2009 Ordinary Level Junior Cert

The Make Up of a Depression

Warm sector and a cold sectorWarm front

Warm air rises over cold airIt cools, condenses and becomes rain

Cold frontCold air nudges under warm airAir rises, cools, condenses and rains

The depression is an area of low pressureWinds blow inwards

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2008 Junior Cert Paper