The Rain Shadow Effect.

Aim: To understand how the rain shadow effect affects the

distribution of rain in England and Wales.

Skill: To interpret data using a choropleth map.

Starter: Describe what you notice about the relief of England and Wales.

Hint: higher land is shown by browner colours

Look up what prevailing winds are, add the definition to your atlas. Do you know where most of England and Wales’ prevailing winds come from?

.

Mountain acts as a

barrier

Moisture is squeezed out of the air Less

likely to rain

Windward sideLeeward side

Prevailing

What is it then?

• Mountain ranges acts as barriers to the flow of air across the surface of the earth.

• As a parcel of air rises up the windward side of a mountain range, it has its moisture squeezed out.

• Thus, when the air begins to descend the leeward side of the mountain, it is dry.

• As the cool air descends, it warms and expands, reducing its possibility of precipitation.

• This is known as the rain shadow effect and is the primary cause of leeward deserts of mountain ranges, such as California's Death Valley.