Lab 4

Orographic Lifting, Apparent Temperature, Satellite Imagery, Radar Imagery, Surface Patterns of Pressure and Wind, Constant Pressure Surfaces

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

● Orographic - of or related to mountains; associated or induced by the presence of mountains

● Orographic Lifting - lifting of air by terrain

● Clouds form when air rises

● Clouds disperse when air sinks

Orographic Lifting

erh.noaa.gov

Apparent Temperature

● What the temperature “feels like” to the average person if the effect of moisture content of the air is taken into account

● AKA “Heat Index,” AccuWeather’s “RealFeel”

● Apparent Temperature = Air Temperature + (Vapor Pressure -16)

● Find the Apparent Temperature:

○ T = 80°F, Td = 70°F

○ Equilibrium Vapor Pressure at 70°F is 25mb

○ Ta = 80 + (25-16) = 89°F

Satellite Imagery - Visible

● Uses visible radiation from the sun back-scattered off objects on the earth

● Meteorologists are able to distinguish between different cloud types because of differences in albedo

● Thick clouds (i.e. Cumulonimbus) have higher albedo than thin, wispy clouds (Cirrus)

● Since it uses radiation from the sun, it’s only useful with daylight

Satellite Imagery - Visible

Satellite Imagery - Infrared

● Uses infrared radiation emitted by the earth and objects near the surface (i.e. clouds)

● Distinguish between high and low clouds based on temperature and the amount of radiation the cloud emits

● Useful day and night since objects always emit radiation

Satellite Imagery - Infrared

Satellite Imagery - Water Vapor

● Water vapor is the dominant emitter of infrared radiation around 6.7 microns

● Satellites are calibrated to measure this radiation so we can get a sense of water vapor in the atmosphere

● 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

● RAdio Detection And Ranging

● Ground-based remote-sensing instruments

● First successfully used in World War II

● 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

● 3 Forces that Control the Wind

○ Pressure Gradient Force (PGF)

○ Coriolis Force

○ Friction

Pressure Gradient Force (PGF)

● The wind is caused by differences in air pressure

● Pressure Gradient Force - force that sets the air in motion in a determined effort to erase the pressure gradient

“THE WIND WILL BLOWFROM HIGH TO LOW”

-Mr. Anderson

Coriolis Force/Coriolis Effect

● 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

● Caused by the rotation of the earth

● CCW rotation around lows

● CW rotation around highs

Friction

● The Earth’s surface is not smooth (mountains, hills, trees, buildings, etc.)

● Acts to slow wind speeds and reduce the effect of coriolis

Lake Erie Wx

Correcting to Sea Level Pressure

● Air pressure decreases with increasing altitude

● What city has a higher surface pressure: Miami, FL or Denver, CO?

● We correct to sea-level pressure because it removes the effect of elevation

Constant Pressure Surfaces (Heights)

● Surfaces (height) at which pressure is constant

● The same pressure does not occur at the same height everywhere, so these surfaces are not flat

Heights and Temperature

Lab 4

● 4.14(a,b)

● 4.15(c)

● 5.4(a,b,c)

● 5.10(a,b)

● 5.18

● 6.2(a,b)

● 6.7(a,b)

● 6.9(a,c,d)

● 7.9(a,b)