Meteorology Exam 2 Chp. 4,5,6,&7

Water in the Atmosphere in Surface

0.6%

Water in the Atmosphere in Ice

2.2%

Water in the Atmosphere in atmosphere vapor

0.001%

Water in the Atmosphere in salt

97.2%

Gas

Water molecules move more freely

They mix well with neighboring molecules and atoms

Liquid

Water molecules are closer together

They constantly numb into each other

Solid

The molecules arrange themselves into an ordinary pattern

Each molecule is "locked" into a ridged pattern

Phases of water: Solid (ice)

Molecules arrange themselves into a ridged pattern

Vibrate against each other

Add energy to molecule to get it to break free

Phase change: water changes its energy

Vapor to liquid

Vapor to solid

Vapor to liquid

Condensation

Vapor to Solid

deposition

Phase Change: liquid (water)

Molecules are close together, bumping and vibrating, moving at slightly different speeds

At surface some require enough to break away

Phase Change: gas (vapor)

Molecules are far apart from each other, zipping past each other

Can be transported great distances

Water Vapor: Saturation

water in the form of a gas

It is covered glass, the number of evaporating molecules will eventually balance the number that are condensing

Molecules escaping

Evaportation

Molecules returning

condensing

What is evaporation larger than?

Condensation

What happens to mixing wind air?

Unsaturated (mor molecules leave the surface and evaporation increases)

Increase wind =

Increase evaporation

Warm water evaporation is faster than?

Cooler water

Warm water=

Molecules move faster

Increase in temperature =

Increase in evaporation

condensation nuclei

tiny bits of particulate matter that serve as surfaces on which water vapor condenses (dust, smoke, salt water)

Warm air

Molecules move fast and spread apart (expand)

less dense (light)

exert less or low pressure

Cool air

Molecules move slower

When does condensation occur?

as the atmosphere is cooled

hydrologic cycle (water cycle)

circulation of water in the atmosphere

Quantifying Humidity

is one way we measure how much moisture in the air

air parcel

a volume of air that has flexible walls and cannot mix with the environment around it

Relative humidity

The ratio of amount of water vapor actually in the air to the maximum amount of vapor required for saturation at that temperature

Warming the air

Will decrease the relative humidity

Cooling the air

Will increase the relative humidity

What are the two ways to change relative humidity

1. Change water content

2. Change temp

What does adding water vapor do?

Increases relative humidity

Daily variation in relative humidity?

30-50%

Dew point

the temperature at which the water vapor in the air becomes saturated and condensation begins

What will Relative humidity be if temp and dew point are equal?

Always 100%

What does it mean when temp and dew point are close together?

Relative humidity is high

What does it mean when temp and dew point are far apart?

Relative humidity is low

Fog

A cloud in contact with the ground

Forms usually when condensation begins to form on less active nuclei (usually when RH is close to 100%)

What are the 2 different ways fog is formed?

1. Cooling the air to it's saturation point (dew point)

2. Melting & evaporation (adding more vapor content to atmosphere)

How is fog forming maintained?

1. Forming new "fog droplets"

2.adding moisture to atmosphere (puddles, lakes, rain, snow melt)

Clouds

Collections of particles of water or ice suspended in the air that are visible above the earth's surface

naming scheme is largely based on thee. work of Luke Howard

Cloud Classification:

stratus

layers

Cloud Classification:

cumulus

heap

Cloud classification:

cirrus

curl of hair

cloud classification:

nimbus

violent rain

The 4 height levels: (abercromby and hidebrandsson)

1. High-level clouds

2. Middle-level clouds

3. Low-level clouds

4. Vertically developed clouds

High clouds

cirrus, cirrostratus, cirrocumulus

-from above 20,000 ft

-almost exclusively "ice crystal" clouds

what do you look at to measure moisture?

dew point

Cirrus cloud (high cloud)

-generally fair & pleasant weather

-most common high cloud

-thin & wispy cloud

precipitation falls when?

air temp and dew point are equal

Dew is most likely to form on

clear, calm nights

cirrocumulus clouds (high cloud)

-small, rounded, white puffs

-isolated, or in rows

-isolated-little piles of sand

-rows-rippling appearance

-seldom cover a small portion of sky

cirrostratus clouds (high cloud)

-thin, sheet-like high clouds

-so thin the sun and moon can shine through

-usually produce a "halo"

-form ahead of approaching storms

middle-level clouds

altocumulus, altostratus

- cloud base: 6,500-23,000ft

- water droplets & ice crystals

- thickest clouds sometimes dim the sun

altocumulus clouds (middle-level cloud)

- gray puffy masse-waves or bonds

- "overcast cloud"

- can look like "castles"

----> castellanus

- precursor of summer afternoon thunderstorm

A rising parcel of air that does not exchange heat with its surroundings is an example of:

adiabatic process

Altostratus clouds (middle-level cloud)

- gray, bluish color-covers the sky

- "milky" look

----> sun is dimly visible

- one big (thin) blanket

- won't see any shadows

if an air parcel is pushed and continues to rise, the atmosphere is said to be?

stable

which type of precipitation would most likely form when the surface air temperature is slightly below freezing and the air temperature increases as you move upward, away from the ground?

freezing rain

suppose the surface air temp is 66F. If the base of a cumulus congests cloud directly over 2,000 ft, what would be the approx. temp at an altitude of 5,000ft above the cloud? (hint: the dry adiabatic rate is 5.5F per 1,000ft, the moisr adiabatic rate is 3.0F per 1,000 ft)

46 degrees

Low clouds

stratus, stratocumulus, nimbostratus, scud

- cloud bases: below 6,500ft

- comprised of water droplets

- gloomy looking sky-often in winter

stratocumulus clouds (low cloud)

-low lumpy clouds

-appear in rows or patches

-blue sky is sometimes visible

nimbostratus cloud (low cloud)

- dark gray, "wet-looking"

- associated with continuous precipitation

-----> (drizzle, rain, and snow)

- very low

- tops can exceed 10,000 ft

- can sometimes break apart

Scud Cloud ( low cloud)

- can sometimes break apart in the wind

- at low height above ground

- found beneath nimbostratus, cumulonimbus, altostratus and cumulus clouds

Stratus cloud ( low cloud)

- uniform, grayish color

- covers the entire sky

- resembles fog (although doesn't touch the ground)

- light precipitation

vertically developed clouds

cumulus, cumulonimbus

- cloud base: 1,000-5,000ft

- cloud tops: 5,000-10,000ft

- compressed of water and ice

true or false: Saturation is more likely to occur in cool air than in warm air

true

true or false: Saturation vapor pressure primarily depends upon air pressure.

false

true or false: During the winter, high relative humidity can irritate the mucus membranes in the nose and throat.

false

A high water vapor pressure indicates a(n)

​relatively large number of water vapor molecules in the air.

As the difference between the air temperature and the dew point increases, the relative humidity

decreases

If the air temperature increased, with no addition or removal of water vapor, the actual vapor pressure would

stay the same

As the air temperature decreases, the ability for the atmosphere to hold additional water vapor:

decreases!

As the air temperature increases, the air's capacity for water vapor

increases

The density of water vapor in a given parcel of air is represented by the

absolute humidity

true or false: The dew point temperature is a measure of the total amount of water vapor in the ai

true

Cirrus clouds are composed primarily of

ice particles

As the air cools during the night, the relative humidity increases. When the relative humidity reaches about 75 percent, condensation may begin on the most active hygroscopic nuclei, producing a ____________________ haze.

moist

true or false: Wet haze restricts visibility more than dry haze.

true

____________________ fog forms when two unsaturated bodies of air mix and the resulting mixture is saturated.

Evaporation (mixing)

​In 1803, Luke Howard, an English naturalist, developed a cloud classification system that employed ____ words to describe clouds as they appear to a ground observer.

latin

If I reported that the sky coverage was 5/8 covered with clouds, the sky condition would be classified as:

Broken (mostly cloudy)

An anvil-shaped top is most often associated with

cumulonimbus

​To a weather forecaster a clear sky is one where no clouds are present. When there are between ____ and ____ clouds covering the sky, there are a few clouds present.

​one-eighth; two-eighth

true or false: On a cold morning, it is possible to see your breath even if the air temperature is above freezing.

true

In a sky filled with scattered cumulus humilis clouds, rising motions are found ____ the clouds and sinking motions are found ____ the clouds.

under, between

The rate at which the actual air temperature changes with increasing height above the surface is referred to as the ____ rate.

environmental lapse

What transfers heat upward into the atmosphere?​

thermals

What two sets of conditions, working together, will make the atmosphere the most unstable?

Warm the surface and cool the air aloft

Which cloud type would most likely form in an unstable atmosphere?

cumulonimbus

Which of the following environmental lapse rates would represent the most unstable atmosphere in a layer of unsaturated air?

11°C per 1,000 m

​In a sky filled with scattered cumulus humilis clouds, rising motions are found ____ the clouds and sinking motions are found ____ the clouds.

under; between

A knowledge of air stability is important because it determines

​the vertical motion of air

A process in which an air parcel expands and cools, or compresses and warms, with no interchange of heat with its surroundings is called a(n):

adiabatic process

The Doppler radar uses the principle called Doppler ____ to measure the speed at which falling rain is moving horizontally toward or away from the radar antenna.​

shift

Fallstreaks most often form with

cirrus clouds

Which is the correct association?

​snow squall - intense snow shower

Supercooled cloud droplets are:

liquid droplets observed at temperatures below 0°C (32°F).