The Cool Temperate Western Maritime climate

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The Cool Temperate Western Maritime climate

• (CTWM)

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CTWM

• Where does it occur?
• Between 40 and 60 North and South of the
  Equator
• Because there is less land mass in the southern
  hemisphere, it is a more common climate type in
  the northern hemisphere
• Maritime means the sea, hence in Europe the
  middle and eastern parts of land masses feel this
  climate less than the western parts (westerly
  winds are most common in this area- from over the
  sea)
• In Europe, the Maritime influence is more clear
  due to the relative warmth of the North Atlantic
  Drift (ocean current)
• In Chile and Canada, the extent of the CTWM is
  restricted because of large mountains (Andes in
  Chile Rockies in Canada)

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What is the CTWM like?

• Prevailing (most common) westerly wind
• Temperature is warmer in summer, cooler in
  winter, but regularly fluctuates
• Pressure is generally lower in winter, higher in
  summer, but like the Temperature, varies greatly
• Precipitation occurs all year round- examples of
  all 3 types of rainfall
• Air masses- the meeting of 2 air masses causes
  the formation of frontal depressions (low
  pressure)

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Climate graph

• Use the data on your sheet to produce a climate
  graph for Fort William, a town in North Western
  Scotland that typically experiences a CTWM climate

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What causes the CTWM Climate?

• Page 57
• Read through the causes section
• Make your own notes on how the CTWM is caused
• Make a neat, full copy of figure 3
• Look at Figure 4- there is a better version for
  you to copy in 2 slides time!

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A Cirrus cloud is seen very high B
Cirro-stratus cloud follows, which is lower and
Alto-stratus cloud is thicker and lower still C
the rain is quite long and steady at this point
due to the long angle of the front and the rising
air and precipitation D Once this has passed
Stratus cloud may give up some water but only in
the form of drizzle and it is quite warm E
Suddenly it goes cold and heavy rain with
possible hail drops accompanied by thunder
(because of the rapid air movements with warm air
rising rapidly from cold air rushing in
underneath) F The trailing weather is cold and
wet G However the greater predominance of
colder dryer air reduces the showers
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What influences Britains Climate?

• Britain is an Island, surrounded by water to its
  western side, and land to its Eastern side
  (generalisation)
• The climate is influenced by 5 main Air Masses
  which pass over Britain at various times of the
  year- as they do they bring distinctive and
  recognisable variations to the climate

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Arctic Maritime
Polar Maritime
Polar Continental
Tropical Maritime
Tropical Continental
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Most common. Mild wet in winter (thick cloud
cover. Warm wet in summer, but not hot. Lower
air is stable, but if forced to rise can be
become conditionally unstable causing thundery
showers
Rare in summer. Very cold in winter, causes snow
Very common. Cold all through the year. Unstable,
causes heavy showers
Only occurs in summer when sub-tropical high
pressure moves north. Heatwave conditions. Very
stable in lower layers may be unstable higher
Mark these comments onto your map in the correct
place- each one is a description of the
conditions one of the 5 air mass brings
Very cold in winter. Stable, but warms crossing
the North Sea to become unstable and snow. In
summer is warm and stable
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Task

• Page 59
• Questions 1 and 2 (Q2 will help with you with
  your HW)

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Task

• Make a comparative study of the precipitation
  between the tropical monsoon and cool temperate
  western maritime types of climate.
• This should take the format of an essay, and
  should carefully go over the differences and
  similarities of the 2 different climates,
  explaining why they occur- use the climate data
  that you have, plus any other data you might find
  out
• 2 Weeks to do it