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Lecture 4. More about Temperature. Incoming vs. Outgoing Radiation. Controls of Temperature. Latitude Land and Water Ocean Currents Elevation. Average Temperature in January. Average Temperature in July. Contouring. EXAMPLE. Contouring. Contouring. Daytime Warming.

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lecture 4

Lecture 4

More about Temperature

controls of temperature
Controls of Temperature
  • Latitude
  • Land and Water
  • Ocean Currents
  • Elevation


daytime warming
Daytime Warming

On a clear, windless day, joggers may experience a temperature of 122oF near their feet, and a temperature of 90oF near their waist.

radiation inversion ingredients
Radiation Inversion Ingredients
  • Windless night
    • Wind mixes the air with turbulent eddies
  • A long night
  • Cloudless night
    • Clouds radiate infrared energy back to surface
  • A dry night
    • If dew forms, then latent heat of condensation is released.
daily low temperature
Daily Low Temperature
  • The lowest temperature may be reached after sunrise. Why?
    • After sunrise outgoing energy still exceeds incoming.
    • The solar angle is low at sunrise
    • If there is moisture, then evaporation cools the air.
measuring temperature26
Measuring Temperature
  • Liquid in Glass Thermometers (mercury or alcohol)
  • Electric Thermometers (used in Automated Weather Stations)
    • Thermocouples
    • Platinum Resistance Thermometers
  • Radiometers (on satellites, weather balloons)
  • Bimetallic Thermometer (thermographs)
wind chill
Wind Chill

Why doe the wind make it feel colder?

  • On cold days our body warms a thin layer of air around us.
  • When the wind blows, this warm layer is replaced by cold air.
  • The faster the wind blows the colder we feel.
The wind chill equivalent temperature tells us how cold it would have to be with no wind, in order for us to lose the same amount of heat.
  • This is new as of 2001!
    • - Replaces Paul Siple’s original work in Antarctica
    • - A bit “warmer” than the old formula
    • -Will be updated in the near future for sunshine
controls of temperature29
Controls of Temperature
  • Latitude
  • Land and Water
  • Ocean Currents
  • Elevation
urban heat island
Urban Heat Island

Stanley Park

Downtown Vancouver

urban heat island32
Urban Heat island
  • Decrease in:
    • Wind speed
    • Humidity (drainage systems take away water!)
  • Increase in:
    • Temperatures
    • Cloudiness
    • Precipitation
    • Fog
    • Pollution
causes of urban heat island
Causes of Urban Heat Island
  • Surfaces
    • Low albedos of asphalt and concrete
  • Heat trapping
    • Tall structures reflect and absorb outgoing radiation
  • Lack of water (rapid water run-off)
    • Less water  less evaporative cooling
  • Surface friction
    • Low wind speed  less mixing
causes of urban heat island34
Causes of Urban Heat Island
  • Human produced heat
    • In buildings, automobiles
  • Particulates and Smog
    • Greenhouse enhancer, traps heat
  • Snow Removal
    • Decreases the albedo
heat island example
Heat Island Example

Areas that are “warm” appear in white/light gray.

Areas that are “cool” appear dark.


heat island example36
Heat Island Example

Trees and vegetation appear in red.

Buildings, streets and urban land cover is white/blue-green/black.

Note the shape of the downtown region.


heat island example37
Heat Island Example

Remember the shape of the downtown!