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Chapter 6

GEOG 1300 Chapter Notes - Chapter 6: Urban Heat Island, Waste Heat, Shifting Cultivation

Course Code
GEOG 1300
John Lindsay

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Chapter 6: Regional and local climates
6.2 Altitude and topography
Lapse rate rate at which temperature decreases with altitudinal increase
Environmental lapse rate the actual rate at which temperature falls with increasing altitude in
the local atmosphere
Conditionally unstable instability in the atmosphere that is conditional upon an air parcel
becoming saturated, which leads to a shift from cooling via the dry adiabatic lapse rate to the
saturated adiabatic lapse rate. This causes the air to become warmer than the surrounding air
and ascend more rapidly, leading to the deep-ocean floor
Super-adiabatic a term used for localized steep lapse rates that are greater than even the dry
adiabatic lapse rate causing rapid local convection
Katabatic drainage radiative cooling at night causes the air close to the ground to cool; this
cooler air is slightly denser and slowly moves downslope to lower ground and into depressions.
It is greatest in cloud-free and dry conditions with light winds (limited mechanical mixing of the
Fohn wind the European equivalent of the Chinook wind
Chinook a warm, dry local wind that blows east down the lee slopes of the Rocky Mountains.
The wind is subject to warming by adiabatic compression on descent and is warmer in absolute
terms at any given altitude than in its windward ascent
Bergeron process the formation of precipitation described by the Bergeron-Findeison theory.
Ice crystals fall from the upper part of a cloud, leading to aggregation of crystals and accretion of
supercooled water. Ice crystals grow preferentially by sublimation at the expense of surrounding
water droplets because the relative humidity above an ice surface is greater than a liquid
surface and hence the saturation vapour pressure over water is greater than ice, causing a
pressure gradient towards the ice
Feeder-seeder mechanism a type of orographic enhancement of precipitation. Adiabatic
cooling of air forced to rise over mountains causes saturation of water vapour and cloud
formation. The water vapour of this ‘feeder’ cloud is swept into the precipitation of a frontal
‘seeder’ cloud aloft, increasing the overall precipitation on the mountain
Sublimate a change in the physical state of a substance directly from solid to gaseous form
6.3 Influence of water bodies
Specific heat the energy required to change the temperature of 1 gram of a substance by 1
degree Celsius. Water has a higher specific heat capacity than air, requiring more energy to be
absorbed for any given temperature change
6.4 Human influences
Roughness length an indicator of the roughness of the ground surface and its impact upon
surface winds
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