Orographic Lifting, Apparent Temperature, Satellite
Imagery, Radar Imagery, Surface Patterns of Pressure and
Wind, Constant Pressure Surfaces
Lab 4
On labs and stuff…
 Please read/answer the whole problem.
 Use units.
 Come to my office hours/ask me anything
 Review for midterm: 10/1 7:30-8:30
Orographic Lifting
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Orographic - of or related to mountains; associated or induced by
the presence of mountains
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Orographic Lifting - lifting of air by terrain
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Clouds form when air rises
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Clouds disperse when air sinks
Orographic Lifting
erh.noaa.gov
Apparent Temperature
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What the temperature “feels like” to the average person if the
effect of moisture content of the air is taken into account
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AKA “Heat Index,” AccuWeather’s “RealFeel”
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Apparent Temperature = Air Temperature + (Vapor Pressure -16)
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Find the Apparent Temperature:
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T = 80°F, Td = 70°F
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Equilibrium Vapor Pressure at 70°F is 25mb
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Ta = 80 + (25-16) = 89°F
Satellite Imagery - Visible
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Uses visible radiation from the sun back-scattered off objects on
the earth
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Meteorologists are able to distinguish between different cloud
types because of differences in albedo
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Thick clouds (i.e. Cumulonimbus) have higher albedo than thin,
wispy clouds (Cirrus)
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Since it uses radiation from the sun, it’s only useful with daylight
Satellite Imagery - Visible
Satellite Imagery - Infrared
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Uses infrared radiation emitted by the earth and objects near the
surface (i.e. clouds)
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Distinguish between high and low clouds based on temperature
and the amount of radiation the cloud emits
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Useful day and night since objects always emit radiation
Satellite Imagery - Infrared
Satellite Imagery - Water Vapor
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Water vapor is the dominant emitter of infrared radiation around
6.7 microns
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Satellites are calibrated to measure this radiation so we can get a
sense of water vapor in the atmosphere
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BUT...a radiometer attuned to radiation at wavelengths near 6.7
microns can only detect water vapor residing in the upper or
middle regions of the troposphere
Satellite Imagery - Water Vapor
Radar Imagery
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RAdio Detection And Ranging
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Ground-based remote-sensing instruments
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First successfully used in World War II
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Radar works by transmitting pulses of radio waves from an
antenna. The pulse is reflected off a “target,” such as a rain
shower, and returns to the radar’s receiver giving us the size and
distance of the target
Radar Imagery
Radar Imagery - Complication
 Height of radar beam increases with distance from radar
 Sometimes overshoots shallow clouds/precipitation
Surface Patterns of Pressure and
Wind
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3 Forces that Control the Wind
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Pressure Gradient Force (PGF)
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Coriolis Force
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Friction
Pressure Gradient Force (PGF)
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The wind is caused by differences in air pressure
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Pressure Gradient Force - force that sets the air in motion in a
determined effort to erase the pressure gradient
Coriolis Force/Coriolis Effect
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The force that deflects objects moving along the surface of the
earth to the right in the northern hemisphere and to the left in
the southern hemisphere
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Caused by the rotation of the earth
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CCW rotation around lows
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CW rotation around highs
Friction
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The Earth’s surface is not smooth (mountains, hills, trees,
buildings, etc.)
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Acts to slow wind speeds and reduce the effect of coriolis
Lake Erie Wx
Correcting to Sea Level Pressure
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Air pressure decreases with increasing altitude
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What city has a higher surface pressure: Miami, FL or Denver,
CO?
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We correct to sea-level pressure because it removes the effect of
elevation
Constant Pressure Surfaces
(Heights)
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Surfaces (height) at which pressure is constant
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The same pressure does not occur at the same height
everywhere, so these surfaces are not flat
Heights and Temperature
Lab 4
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4.14(a,b)
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4.15(c)
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5.4(a,b,c)
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5.10(a,b)
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5.18
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6.2(a,b)
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6.7(a,b)
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6.9(a,c,d)
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7.9(a,b)