METC Exam 3 Pt 1

500 mb staitonal models are good for

assessing cyclones

500 mb is how many miles up?

3.5 miles up

Pressure is a ____ _____ for 500 mb charts

vertical coordinate

the 500 mb chart is the

most important chart

isoheights also mean

pressure

Isotherms also mean

temperature

Td > 0

Dew point depression

Td < 0

actual dew point

absolute isoheights

low values = cold column of air from surface to 500 mb

high absolute isoheights are

warm

relative isoheights

troughs and ridges, gives us a sense of wave pattern

Convergence aloft leads to

surface high, anticyclogensis

Divergence aloft leads to

surface low, cyclogenesis

air converges at _____ ______ and raises _____

surface lows, pressure

due to air converging at surface lows and raising pressure, we must have

divergence aloft (cyclogenesis)

To measure divergence aloft we have to assume that

winds aloft are geostrophic

Geostrophic winds are

parallel to isoheights

Vorticity is

measure of spin of air parcels, z axis

cyclonic is positive and

CCW

anticyclonic is negative and

CW

Earth vorticity is the smallest at the

equator

Earth vorticity

Earth rotates. all air has rotation relative to earth’s axis

Earth vorticity

f = 2 x omega x sin theta

Earth vorticity increases as ____ increases

latitude

Earth vorticity is the largest at the m

poles

Increase in vorticity leads to ____ aloft, and ____ spin

convergence, faster

Decrease in vorticity leads to ____ aloft, and ____ spin

Divergence, slower

Relative vorticity

rotation moving through ridges and troughs

With relative vorticity, it is ___ in ridges and ____ in troughs

negative, positive

Absolute vorticity

Earth vorticity + relative vorticity

F_earth ___ F_relative

>

Absolute vorticity is almost always

> 0

Absolute vorticity is a ____ in ridges and ____ in troughs

minimum, maximum

Vort increases → ___ spin → _

faster, convergence

Vort decreases → ___ spin → _

slower, divergence

Ideal location for surface cyclones

just east (downstream) of 500 mb troughs

what happens east/downstream of 500 mb troughs

Div aloft, surface pressure falls, cyclones form

Air is diverging is ___ / east of trough, caused by __, and associated with

ahead, PVA, t storms, clouds, surface lows

Air is converging is ___ / east of ridge, caused by __, and associated with

ahead, NVA, clear skies, and surface highs