G1250 - Exam 2 Flashcards
notes from slides and questions from exam
what is the definition of vapor pressure (e)
(e) is the amount of pressure in mb exerted by water vapor in the air
vapor pressure (e) is the measure of the
actual vapor content of the air
when evaporation rate is equal to the condensation rate it means that
vapor pressure is at equilibrium (saturated)
what is the definition of saturation vapor pressure (es)
es is the vapor pressure of the air when the air is saturated
es is the measure of the
maximum vapor content of the air
es is the pressure exerted by the
maximum amount of vapor that can be in the air at a given temperature
what is saturation
e=es
what is subsaturation
e<es
what is supersaturation
e>es
what is the definition of relative humidity
the actual vapor pressure of the air (e) relative to (/) the vapor pressure exerted by the air if it were saturated (es)
what is the formula for RH
RH=e/es *100%
vapor pressure is a measure of the
actual rate content of the air
saturation vapor pressure is a measure of the
maximum vapor content of the air at a given temperature
when air temperature increases the
saturation vapor pressure increases
when air temperature increases the saturation vapor pressure
increases exponentially
what is the formula for dew point depression
DPD= t-td
DPD is the approximate measure of
RH
aerosols are made of
dust, smoke, and pollen
what is the range of aersols
0.2-10um
as aerosols concentration decreases as size
increases
what is a hygroscopic aerosols
when condensation when RH<100%
what is hydrophobic aerosols
when there is no condensation when RH>100%
condensation wil not occur if nuclei are
not present
what happens when condensation occurs in the atmosphere when the earths surface cools overlying air
it creates fog
what happens when condensation occurs in the atmosphere when rising air causes expansional cooling
it creates clouds
what are the three types of fog
radiation fog
advection fog
steam fog
how does radiation fog form
forms during clear calm nights
earths surface cools the overlying air to Td
additional cooling causes condesnation to occur
how does advection fog form
forms both during the day and night
air with Td greater than surface T advected by wind over surface
often occurs during snow melt
how does steam fog form
forms over warm bodied of water
cold air advanced by the wind over the water
water warms the overlying air
water evaporates into the air
warm moist air rises via convection
when water vapor condenses to form a cloud droplet
it does so on a condensation nucleus
fog forms when
saturated air is cooled at the earths surface
why do clouds forms
clouds forms when saturated air is cooled
warm clouds are how warm/cold?
T>32 degrees f
warm clouds are
all liquid and no ice
warm clouds:
collision and coalescence
larger droplets collide and merge/coalesce with smaller droplets
efficiency increases as droplet size increases
cold clouds form when temperateures are
T<32 degrees f
ice clouds are ice crystals which are
supercooled droplets and vapor
cold clouds are Deposition nuclei wich are
hexagonal and rare
cold clouds composed almost entirely of
supercooled droplets
step 1 of the Bergeron Process
vapor deposits on crystal
ice crystals grown and e decreases
step 2 of Bergeron Process
crystal growth decreases
droplets evaporate and e increases
step 3 & 4 of Bergeron Process
vapor deposits on crystals
crystal growth increases and e decreases
step 5 of the Bergeron Process
RHi = 100%
deposition = sublimation
crystal growth stops
what is the definition of the Bergeron Process
the process by which ice crystals grow at the expense of supercooled droplets in a cold cloud
a cold cloud is comprised almost entirely of supercooled water droplets because
deposition nuclei are hexagonal and rare
within a cold cloud there exists a single ? and ?
temperature and vapor pressure
in a cold cloud, more vapor is required to saturate the air around an
supercooled water droplet
the Bergeron process occurs n a cold cloud because the air around ice crystals is ? and the air around supercooled water droplets is either
supersaturated, saturated or subsaturated
the Bergeron process will continue in a cold cloud until all of the ?
supercooled droplets have evaporated
precipitation falls as snow when
air temps remain below freezing throughout the atmosphere
partly frozen drops refreeze and become sleet when
it starts as snow, falls through a shallow warm layer, and then falls through a deep cold layer
when rain drops become “supercooled” in cold air and freeze on contact causing
Freezing rain
a cold cloud is comprised almost entirely of supercooled water droplets because ?
deposition of nuclei are hexagonal and rare
within a cold cloud there exists a single ? and ?
temp and vapor pressure