Weather and Climate

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Weather and Climate
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Weather

• Environmental conditions that occur at a
  particular place at a particular time

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Climate

• Average weather conditions that occur in a region
  over a long period of time (usually 30 years)

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Both include

• Temperature, humidity, rainfall, air pressure,
  wind and numerous other meteorological elements

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Climate is what you expect, weather is what you
get.
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Importance of Climate

• Determines what producers can live in an area and
  this affects all other organism as producers are
  the base of food chains.
• Affects type of housing, clothing, etc for people
  living there

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Climate Systems ? Energy comes from the Sun
? Sun emits all types of radiation including
ultraviolet (short wavelength, high frequency),
visible and infrared radiation (long wavelength,
low frequency) ? Radiation may be absorbed by
particles, transmitted through particles or
reflected off particles
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Do NOT need to memorize these numbers!
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Land and oceans absorb 51 of solar energy

• As Earth absorbs energy from the sun,
• the Earths surface gains thermal energy
• (increased motion of particles) and temperature
  rises
• Earths surface then emits mostly infrared
  radiation back out

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Greenhouse Effect

• A NATURAL process whereby gases and clouds absorb
  infrared radiation emitted from Earths surface
  and radiate it, heating the atmosphere and the
  Earths surface

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• If Earths atmosphere was thicker, it could
  retain TOO much heat
• E.g. Venuss atmosphere is 100 times more dense
  than Earths
• Its surface temperature is about 700oC
• If Earths atmosphere was less dense, it might
  not retain enough heat
• E.g. Mars atmosphere is 100 times less dense
  than that of Earth
• Its surface temperature is about -630C

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• Without an atmosphere (without greenhouse
  effect), Earth would have an average temperature
  of about -18oC
• instead of its actual average around 150C

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• It would also get extremely cold at night because
  it would have nothing to retain some of the heat
  gained during the day!!
• E.g. Mercury has no atmosphere
• Its temperature reaches 4500C during the day and
  then drops to -1700C at night!!!

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• The greenhouse gases include
• water vapour
• carbon dioxide
• methane
• nitrous oxide

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HINTS FOR EXAM

• You should be able to
• Explain difference between weather and climate
• Explain the greenhouse effect
• Explain how the greenhouse effect is partially
  responsible for our global temperature
• Name the greenhouse gases