Download The sequence of a depression As the cold front arrives, there are

The sequence of a depression
In the UK depressions occur when the warm, moist air mass from the tropics meets the cool,
dense air mass from the polar region. This is a weather front. Small waves in the front can
develop into depressions with a well-developed warm sector and both cold and warm fronts.
Depressions usually take between 12 and 24 hours to pass over a location. As the depression
passes, there are recognisable changes in the weather.
Student task: Cut the cards out and rearrange them to give the correct sequence for
the passage of a depression over the UK.
As the cold front arrives, there are large, high cumulonimbus clouds and very heavy
rain. The temperatures fall.
Temperatures will rise, often by approximately 6 to 12°C. There is some light, high
cloud and it is mostly dry.
High cirrus cloud is visible in the west. Temperatures are cool. There will be little
or no rain.
The heavy rainfall will die out and be replaced by a mixture of sunshine and heavy
showers.
Altostratus and nimbostratus clouds will continue to form as the warm front
approaches. Rain will begin to fall steadily.
A METEOSAT9 infrared satellite image of the UK and the Atlantic Ocean on July 6, 2010. The image
shows a depression passing over the UK.
Image courtesy of the National Oceanic and Atmospheric Administration, USA.
http://www.vos.noaa.gov/MWL/dec_10/northatlantic.shtml
© www.teachitgeography.co.uk 2012
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The sequence of a depression
Answers
1.
High cirrus cloud is visible in the west. Temperatures are cool. There will be little or
no rain.
2.
Altostratus and nimbostratus clouds will continue to form as the warm front
approaches. Rain will begin to fall steadily.
3.
Temperatures will rise, often by approximately 6 to 12°C. There is some light, high
cloud and it is mostly dry.
4.
As the cold front arrives, there are large, high cumulonimbus clouds and very heavy
rain. The temperatures fall.
5.
The heavy rainfall will die out and be replaced by a mixture of sunshine and heavy
showers.
© www.teachitgeography.co.uk 2012
18559
Page 2 of 2