Regional Weather

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Regional Weather
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Thermals

• Thermals are a rising current of warm air caused
  by convection it is also known as an updraft.
• The sun heats up the land and the air just above
  the land heats up and rises. This rising, warm
  air is our thermal.
• Balloonists and gliders depend on thermals to
  help give them lift.

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Sea Breezes

• Wind can be caused by the land near a large body
  of water heating up and creating thermals.
• The air over the land rises and when it rises,
  the air over the water moves in to take its
  place.
• The air in the thermals cools and drops down to
  take the place of the air that moved in from over
  the water.

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Sea Breeze Formation
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Land Breezes

• Land breezes are the reverse of sea breezes. They
  occur later in the day as the temperature is
  dropping.
• The land cools much quicker than the water (which
  stays warmer longer).
• The air above the warmer water rises as thermals
  and is replaced by cool land air.
• The warm air then cools and replaces the air that
  was once over the land.

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Land Breeze Formation
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Lake-Effect Snow

• Lake-effect snow occurs during the winter when a
  wind sweeps across a large body of water that has
  retained some heat from the warmer weather
  earlier in the year.
• The wind picks up some moisture from the lake and
  carries it up over the land.
• The land is much colder than the lake so the
  moisture cools and condenses and falls as
  precipitation (snow).
• Much of the snowfall experienced by the Durham
  Area is the result of Lake-effect snow.

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Lake-Effect Snow Formation
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Chinook Winds

• Chinook winds are seen in Western Canada and are
  caused by the mountains and orographic lifting.
• The orographic clouds form by moisture condensing
  as it rises up the mountain. This condensation
  releases heat that stays in the air and travels
  down the other side of the mountain and out over
  the prairies as a dry, warm air mass.

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Chinook Wind Formation
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Precipitation Humidity
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Precipitation

• Precipitation is any water that reaches the
  ground in either a liquid or solid form.
• The type of precipitation that falls depends on
  the temperature on the ground and in the
  atmosphere.
• Types of precipitation may include
• Drizzle
• Rain
• Freezing Rain
• Snow
• Ice Pellets (Sleet)
• Hail

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Humidity

• Humidity is the measure of the amount of water in
  the atmosphere.
• Low humidity means that the evaporation of sweat
  from our body can take place easily because there
  is a lot of room in the air for it.
• A high humidity means that sweat sticks to us
  because the air already has a lot of moisture in
  it and there is no room for extra moisture from
  us.
• Relative humidity is a measure of the moisture in
  the air against the maximum amount of moisture
  the air could actually hold at a given
  temperature. It measured as a percent.

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