Atmospheric Moisture - Chap 6

Question 1

Absolute humidity
(Upside down A - V)

Answer 1

Mass of water vapor in given VOLUME of air
(expressed as grams water/cubic meter air)

Question 2

Specific Humidity

Answer 2

Mass of water vapor in given MASS of air (grams water vapor per kg of air)

Question 3

Saturation specific humidty

Answer 3

maximum specific humidity at a given temperature

Question 4

Vapor pressure

Answer 4

contribution of water vapor to total atmospheric pressure
(saturation vapor pressure - max vapor pressure at given temp)

Question 5

How to calculate relative humidity

Answer 5

(actual water vapor in air / capacity) * 100

Question 6

Factors affecting relative humidity

Answer 6

amount of evaporation + condensation (affects numerator)
temperature (affects capacity aka denom)

Question 7

Temperature + relative Humidity relationship

Answer 7

INVERSE
increase in temperature –> decrease in relative humidity
WHY? Increasing temperatures INCREASE capacity to hold water (bigger denom) making overall fraction smaller

Question 8

Dew point temp

Answer 8

temperature air must cool to saturate

Question 9

sensible temperature

Answer 9

temperature person’s body feels

Question 10

what impacts sensible temp

Answer 10

actual air temp, relative humidity, dew point, wind

Question 11

Condensation

Answer 11

opposite of evaporation, occurs when air is saturated BUT need to have a surface for condensation to occur on
(air can become supersaturated if no surface is available + cooling continues)

Question 12

Condensation nuclei

Answer 12

tiny particles (particulates) in air
hydroscopic SO serve as collection points for water molecules –> eventually form raindrops

Question 13

What is the only prominent mechanism for cloud development + rain

Answer 13

adiabatic cooling
(air rising, pressure decreases + expands and cools)

Question 14

Dry adiabatic rates

Answer 14

when parcel of unsaturated air rises, it cools at rate of 10 degrees C/1000 meters

Question 15

Lifting condensation level

Answer 15

when parcel of air rises enough to become saturated, start condensation, form clouds

Question 16

Saturated adiabatic rate

Answer 16

ABOVE LCL
slower cooling bc latent heat released from condensation counteracts the adiabatic cooling,
~6 deg C/1000 meters

Question 17

Why can’t clouds form going DOWN

Answer 17

Adiabatic warming = descending air warms, which increases water vapor capacity SO condensation will never happen –> no clouds

Question 18

3 cloud forms

Answer 18

1) Cirriform
2) Stratiform clouds
3) cumuliform clouds

Question 19

cirriform (lock of hair)

Answer 19

thin, high, ice crystals instead of water droplets

Question 20

Stratiform (spread out)

Answer 20

grayish sheets covering most of sky, rarely broken into individual units

Question 21

cumuliform (heap)

Answer 21

massive rounded, with flat base + tend to be very tall

Question 22

Cloud names

Answer 22

if they have “nimb” in it –> produce precipitation

Question 23

4 types of fog

Answer 23

1) radiation fog
2) advection fog
3) upslope (orographic) fog
4) evaporation/steam fog

Question 24

radiation fog

Answer 24

forms when ground radiates heat at night –> air warms up + rises away, replaced by cooler air that turns into fog
collects in low areas

Question 25

advection fog

Answer 25

develops when warm, moist air ADVECTS (horizontally moves) over cold surface (snow covered ground, ocean current)
air moving from sea to land most common source of advection fog

Question 26

upslope (orographic) fog, oro = mountain

Answer 26

created by adiabatic cooling when humid air climbs mountain/slope

Question 27

evaporation/steam fog

Answer 27

water vapor added to cold air that is near saturation
occurs when cold air flows over warm body of water

Question 28

4 types of atmospheric lifting

Answer 28

Convective, orographic, frontal, convergent

Question 29

Convective lifting

Answer 29

Parcel of air heated by ground bc of convection + rises by convective lifting
expands + reaches dew point temperature, condenses, forms cumulus cloud

convective precip = showery w. fast large raindrops

Question 30

orographic lifting

Answer 30

occurs when wind encounters mtn, forced to go up by orographic lifting –> produces precip if rising air cooled to dew point

Question 31

rain shadow

Answer 31

occurs bc orographic lifting essentially stops climbing up + then starts descending –> leads to adiabatic warming + cloud goes poof

Question 32

frontal lifting

Answer 32

caused by unlike air masses meeting, forming a front (unlike air masses DO NOT mix)

warm air rises over cool air, adiabatically cools, forms clouds + precip

*characteristic of midlatitudes bc of meeting grounds for cold polar air + warm tropical air

Question 33

Convergent lifting

Answer 33

when air converges –> general uplift –> causes instability + produces showery precipitation
common in ITCZ + in cyclonic storms