Climatic Hazards and Change

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Climatic Hazards and Change

• Core Concepts in Physical Geography

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Part 1 Costs and Benefits of Weather and Climate

• The difference between Weather and Climate is
• Weather is the conditions of the atmosphere
  outside right now
• Climate is the average weather recorded over a
  long period of time- normally at least 30 years

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Atmospheric processes which affect climates

• The main ways that climate is influenced around
  the globe are
• Solar radiation (Latitude)
• Distribution of land and sea
• Ocean Currents
• Prevailing winds, surface heating and pressure
• Altitude

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Solar radiation

• The sun shines at a high angle, directly over the
  equator for most of the year
• The direct approach means there is little
  radiation lost in the dust and atmosphere
  surrounding the earth
• In the higher latitudes the angle is lower,
  meaning the sun heats a larger surface area. More
  radiation is also lost in the atmosphere
• Because of this variation, seasons are more
  pronounced in the higher latitudes

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Ocean Currents

• Ocean currents circulate the globe, and with it
  help even out global temperature. Copy the info
  from above onto the blank world map outline.

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Altitude

• You did this last year
• Very simple concept- the higher up you go, the
  cooler it becomes
• The general rule is that it becomes 10 degrees
  Celsius cooler for every 1000 metres up you go

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Prevailing winds

• Another simple concept
• Make a copy of this picture, and annotate it with
  notes from what is said-

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Distribution of land and sea

• 90 of all the land in the world is in the
  northern hemisphere
• 70 of the surface of the globe is covered in
  water
• The sea has an almost constant temperature around
  most of the world
• Winds that blow across the sea are warm in the
  winter and cool in the summer
• Winds that blow across the land are cool in the
  winter and warm in the summer

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Pressure

• 3 separate cells are of great importance in
  controlling the weather and climate in the
  surface areas below them
• In 2 places- at the equator, and at 60 degrees
  north / south, air is rising- forming clouds and
  rain (depressions)
• Important words- Hadley cell Ferrel cell,
  ITCZ

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Global circulation model, shown from the side
(Northern Hemisphere)
Make a neat, coloured copy of this diagram
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Global wind circulation
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What is the ITCZ?

• The Inter-Tropical Convergence Zone (ITCZ) is the
  area around the middle of the globe where
  tropical air flows meet
• The air masses that are meeting are both warm
• There is also intense overhead heating from the
  sun in this area
• Because of this the ITCZ is known as an unstable
  area where there can be much rainfall
• The ITCZ stays close to the Equator except for in
  the summer, when it rises to be over India

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Using a blank outline map, and Figure 2 on page
53, make a neat, labelled and titled map of the
ITCZ in June
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Location of Tropical monsoon and Temperate climate
Page 53- make a neat copy of this map onto a
blank world map outline
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Task

• Page 53-
• Answer questions 1, 2 3
• Read over any notes that will help you with the
  work done so far

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The Tropical Monsoon Climate (TM)

• Means Season in Arabic
• It is a seasonal wind reversal
• These reversals occur throughout the tropical
  region, but are best seen in the area around
  India
• There is a massive variation in the Monsoon
  climate even within the Indian subcontinent
• This is a major case study for this part of the
  unit (especially when comparing it to Cool
  Temperate Western Maritime climate (CTWM)

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What is the Monsoon like?

• Rather than me just tell you-
• Read through the characteristics section on page
  54, and put into your own words the 3 categories
• March-May
• June-September
• October-February

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Causes of the Monsoon
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Monsoon-continued

• Temperature in monsoon high all year
• Intense summer rainfall (mainly convectional)
• Winter drought
• Onshore wind in summer brings moist air
• Pressure is low in summer, high in winter
• The ITCZ is moving north in the summer bringing
  with it low pressure
• The heating of the landmass of Asia and India
  creates low pressure- these two areas of low
  pressure then suck in the moist air from the
  south (from over the ocean)
• The downpours that follow are intense, especially
  in the higher altitude regions
• This all changes from mid-September
• The ITCZ retreats south
• The North East Trade winds (offshore) blow in a
  south-westerly direction, bringing dry weather,
  and a high pressure winter

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Task

• Go to www.worldclimate.com
• Type in Shillong
• Find out the average temperature and average
  rainfall for Shillong, and produce a climate
  graph
• Describe the graph, and try to explain it using
  your knowledge of the Monsoon season