The document discusses the formation of depressions and includes stages of how a depression forms from polar air interacting with tropical air. It also includes facts about depressions, such as they always spin anticlockwise in the northern hemisphere and bring cloud, rain and winds. Links are provided to resources about weather maps and pressure systems.

1. Unfortunately this map showing where the highs and lows are
has been damaged! Can you fix it?

2. The weather today - are we
experiencing a high or a low?
Check it out…….
http://www.bbc.co.uk/weather/ukweather/pres
sure.shtml#no_url

3. Thursday
1pm
What is
happening
here?

4. How does a depression form?
The stages the formation of a
depression

5. Stage 1
Polar air travels towards
tropical air
Pm
Tm

6. Stage 2
Cold polar air starts to cut under the
lighter, warm tropical air making it
rise. The rising air creates a low
pressure on the ground
Pm
Tm

7. Stage 3
A spinning depression is formed
with a warm front and a cold
front. Winds always spin
anticlockwise.
Pm
Tm

8. Stage 4
The depression starts to
die as the warm air is
forced to rise
Pm
Tm

9. Stage 5
A weakened depression. Wind
speeds slow down (isobars
spread apart) and the rain
ceases

10. http://whs.moodledo.co.uk/mod/resource/view.php?id=973

11. Depressions - top 5 facts!
1. Always low pressure (air is being forced to rise)
2. Always spin anticlockwise in the northern
hemisphere
3. Have a warm front, warm sector, cold front, and
sometimes an occluded front
4. Bring cloud, rain and winds
5. Very common in the UK and Ireland.

12. What's an occluded front?
When the cold front catches up with the
warm front and lifts it off the ground!

17. Can you add labels to this map?
Try to add the
following
1. Centre of Low
2. Warm front
3. Cold Front
4. Warm sector

18. Can you add labels to this map?
Try to add the
following
1. Centre of Low
2. Warm front
3. Cold Front
4. Warm sector

19. Can you add labels to these maps?
• http://www.bbc.co.uk/weather/ukweather/pr
essure.shtml#no_url
• http://www.metoffice.co.uk/
• http://www.weather.org.uk/charts/UKCpf036.
gif

21. X – Section of a Depression