Geography 101 Exam 2 Review
what is the average environmental lapse rate?
6.5 degrees c/1000m
T or F: air moves from low pressure to high pressure
F high to low
why does the adiabatic rate of cooling change when condensation begins? why is the adiabatic rate not a constant figure?
because the amount of latent heat released depends on the quantity of moisture in the air and....
what precipitation takes place in warm clouds
bergeron
what are four ways that humans have attempted to alter precipitation patterns?
cloud seeding, fog dispersal, hail suppression, and frost prevention
which air parcel will hold more water vapor, cold or warm?
cold
explain why a cold, dry air mass produces a higher surface pressure than a warm, humid air mass
cold air has a higher pressure than warm air and dry air is heavier than moist air. Moist air has a lower pressure.
absolute stability occurs when a parcel of air is warmer or colder than the environment?
colder
what precipitation takes place in cool clouds
collision-coalescence
what is the level at which clouds form called?
condensation level
DALR> ELR> WALR
conditional instability
compare convergence and divergence
convergence is winds blowing into a region, air piles up and rises, surface pressure increases. divergence is wind blowing out of a region and pressure decreases
does collusion coalescence occur in warm clouds or cool clouds?
cool
what type of cloud is associated with thunderstorms
cumulonimbus
what type of clouds is associated with an anvil top that is composed of cirrus clouds?
cumulonimbus
what would a highly vertically developed rain producing cloud called
cumulonimbus
absolute instability produces what type of clouds?
cumulus
the increase in temperature with height is called________
decrease lapse rate
if air is converging at the surface, what is doing aloft?
diverging
at what rate does unsaturated air cool when it rises through the atmosphere?
dry adiabatic lapse rate 10C/1000m
clouds are typically seeded with what type of substance?
dry ice and silver iodide
what types of fog is common in early fall, and can commonly be seen in or around pools and lakes?
evaporation (steam) fog
clouds are named based on what two criteria?
form and height
what are the units for the mixing ratio calculation?
g/kg
where and why do we change form the DALR to WALF
goes from being unsaturated to saturated
what are the units of absolute humidity?
grams/meter^3
cirro
high clouds
what type of weather is associated with high pressure and low pressure?
high pressure is nice weather and low pressure is rainy or snowy weather
cold air=_______pressure
higher
stratus
horizontal, may be layered (stable) low
does pressure increase or decrease with altitude?
increase
why is the mixing ratio rarely used in forecasting?
it is very hard to calculate by direct sampling
the decrease in temperature with height is called ________
lapse rate
when the atmosphere is stable it will resist vertical movement, sometimes these parcels are forced aloft, what causes this?
lifting mechanisms
what is the difference between low pressure and high pressure?
low pressure air is left behind when air rises and upward moving air doesn't press down hard on the surface, and high pressure air is sinking down air and pushing hard on the surface
warm air=_______pressure
lower
alto
middle
what are the three units used to measure atmospheric pressure?
millibars, inches of mercury, and hectopascals (hPa)
________ and ________ cause the relative humidity to change
moisture content and temperature
what is graupel?
occurs when ice crystals and supercooled cloud droplets bang into each other becoming a spongy mass of frozen water. contains air packets
what are the 4 mechanisms that cause air to rise?
orographic lifting, frontal wedging, convergence, convection
wind speed and direction are controlled by what three factors
pressure gradient force, coriolis force, and friction
what type of fog is produced for the cooling of land after sunset?
radiation fog (ground fog)
nimbo
rain producing clouds
absolute instability occurs when a parcel of air is warmer or colder than the environment at all levels
warmer
absolute instability occurs when a parcel of air is warmer or colder than the environment?
warmer
what are the main two factors that affect atmospheric pressure?
water vapor content and temperature
why is moist air less dense than dry air?
water vapor is a lighter gas
T or F: the mixing ratio is affected by temp. and pressure
F
T or F: there is a greater evaporation over continents than oceans
F
how do updrafts help in the formation of precipitation?
-carries smaller cloud droplets up into the cloud while larger droplets stay suspended within the cloud -some of the droplets collide with one another
what are the two precipitation formation processes? which is associated with rainfall and warm air? which is associated with snowfall and cold air?
-collision and coalescense warm air and rainfall -bergeron cold air and snowfall
what are the three types of lapse rates associated with adiabatic temperature change?
-environmental lapse rate, dry adiabatic lapse rate, and wet adiabatic lapse rate
describe each of the four uplift mechanisms
-orographic lifting- air is forced to rise over a mountainous barrier -frontal wedging- warm air is less dense and rides up over cold air, cold air is more dense and wedges underneath warm air -convergence-a pile up of horizontal air flow results in upward movement -convection- unequal surface heating causes localized pockets of air to rise because of their buoyancy
name and describe the six types of fog
-radiation fog- ground starts to get cold and in the morning cools the air touching the ground -valley fog- the valleys slopes are more exposed getting colder faster at night and cold air drainage into the base of the valley -upslope fog- when relatively humid air moves up a gradual slope and with upward movement air expands and cools to dew point -advection fog- warm moist air is sliding horizontally over a cold surface cooling it to dew point. -evaporation (steam) fog- cold air cant hold excess moisture because water is evaporated but then condenses in the cold -precipitation fog-rain falls through air, continuous misting of air that evaporates into air before reaching ground adding moisture to the air and cooling down the air.
understand the temperature profiles for the following types of precipitation: rain, snow, sleet, and freezing rain.
-rain- snow falls into warm air, melts into rain -freezing rain- snow melts, hits the cold air, freezes when it hits something -sleet- snow melts refreezes into sleet as it travels through cold air -snow-falling into cold air, it never melts on way down
the dry adiabatic lapse rate is constant, at ____ degrees c/1000m
10 degrees c/1000m
how big are rain drops relative to cloud drops
100 times
what is the relative humidity when the air is saturated?
100%
what is the standard sea level pressure?
1013.25 mb=1013.25hPa=29.92 in Hg
what causes water to change state? keep in mind the kinetic energy and molecular structure
As water is boiled, kinetic energy causes the hydrogen bonds to break completely and allows water molecules to escape into the air as gas (steam or water vapor). When water freezes, water molecules form a crystalline structure maintained by hydrogen bonding. Solid water, or ice, is less dense than liquid water.
T or F: absolute humidity is commonly used in forecasting
F
ELR< DALR & WALR
Stable
T or F: Relative humidity is a measure of how near the air is to being saturated
T
T or F: the atmosphere is stable when the environmental lapse rate is less than the wet adiabatic lapse rate.
T
T or F: the dew point temperature will never be greater than the air temperature
T
T or F: the majority of freshwater on the planet is found in ice
T
T or F: the total water vapor in the atmosphere remains constant
T
cumulus
vertically developed (unstable)
cirrostratus clouds cause a unique feature around the sun and moon, what is this feature?
a broad layer of air is lifted by convergence
if a raindrop becomes two large, what will occur?
a droplet can become too large and push others out of the way and cause it to break apart again and have to start the process over
why is absolute humidity not used in forecasting?
absolute humidity depends on volume and volume varies from place to place so it is hard to use
what name is given to the process whereby the temperature changes without the addition or subtraction of heat?
adiabatic temperature changes
what kind of fog is formed when warm air moves horizontally over a colder surface
advection fog
what type of fog is associated with horizontal movement of warm moist air across a colder surface?
advection fog- fog in san francisco
what are the two ways that fog can form?
air cooled to dew point or moisture added
how are winds formed?
air moves from high to low pressure
what is virga?
any form of precipitation that does not reach the ground
at what point of the day is relative humidity highest, when is it lowest?
at night it is highest and at midday 2 it is lowest
when is relative humidity highest during a tropical day? When is it lowest?
at night when temps are lowest, it is lowest in mid day when the temp is highest
why is the mixing ratio calculation not affected by changes to pressure and temperature?
because it is measured in units of mass
what type of clouds and precipitation is associated with a stable atmosphere?
stratus
the shape of a snowflake is dependent of ________ and ________.
temperature and vapor pressure
what occurs when the air temperature and dew point temperature are equal?
the air is saturated
ELR> DALR & WALR
unstable
how is hail formed?
updrafts carry a particle into the colder reaches of a cloud, and the liquid water coats the particle -changes from freezing to melting until it gets big enough to fall out of cloud
why is the wet adiabatic lapse rate highly variable?
varies depending on moisture
