MET1010 (Modules 4-6)

Water Vapor Measures

the part of the total pressure due to water vapor molecules (Mb=millibar's)

Saturation Vapor Pressure

vapor pressure → that part of the total pressure due to water vapor molecules in saturated air (Mb=millibar's)

Saturated

air is holding as much water vapor as it can → reached capacity → has to be 100%

Mixing Ratio

weight of water vapor / weight of dry air = g/kg

Saturation Mixing Ratio

weight of water vapor / weight of saturated air = g/kg

Warm air can hold more water vapor then cold air

True

Changes in Relative Humidity:

• Increase in Temp →

Decrease in Relative Humidity

Changes in Relative Humidity:

• Decrease Temp →

Increase in Relative Humidity

Typical Day → Relative Humidity

Highest: Sunrise | Lowest: 3-5 pm

Dew Point

The temperature the air must be cooled to in order to reach saturation

When the temperature is equal to the dewpoint there is…

100% humidity 

Sling Psychrometer

Calculates dew point temp & relative humidity

Clouds

massive accumulations of either water droplets or ice crystals

______ occupy or cover approximately 70% of the earth's surface

oceans

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

increase

When the air temperature increases, the saturation vapor pressure will

increase

What fogs form from cooling?

Radiation, Advection, and Upslope

How are clouds classified?

Height and appearance

Relative humidity changes with

all choices are correct 

The percentage of water vapor present in the air compared to that required for saturation is the

relative humidity

If very cold air is brought indoors and warmed with no change in its moisture content, the saturation vapor pressure of this air will ____ and the relative humidity of this air will ___

decrease, increase

Dew is most likely to form on…?

clear, calm nights

When naming clouds, the term "strato" means

layer clouds

A low, lumpy cloud layer that appears in rows, patches or rounded masses would be classified

stratocumulus

A dim, watery sun visible through a gray sheet-like cloud layer is often a good indication of ____ clouds.

altostratus

An anvil-shaped top is most often associated with

cumulonimbus

Cirrus clouds are composed primarily of

ice particles

Detached clouds of delicate and fibrous appearance, without shading, usually white in color and sometimes of a silky appearance are

cirrus

Light or moderate-but-steady precipitation is most often associated with ____ clouds.

nimbostratus

In middle latitudes, which cloud will have the lowest base?

stratocumulus

Frost forms when

all of these

This instrument uses wet-bulb and dry-bulb temperatures to obtain relative humidity

sling psychrometer

The cooling of the ground to produce dew is mainly the result of

radiational cooling

The ____ is an apparent force created by the earth's rotation

Coriolis force

Collision-coalescence process is

how rain forms in warm clouds where larger cloud droplets fall faster than smaller ones, collide with them, and merge together (coalesce) to form raindrops large enough to fall to the ground

Bergeron Process

describes how ice crystals grow in cold clouds where supercooled water (liquid water below 0°C) and ice crystals coexist

Supercooled water droplets

are liquid water droplets existing below their normal freezing point of 0°C (32°F).

Condensation Nuclei

surfaces that water vapor condenses on

Absolutely Stable

< 5°C/km

Parcel

a body of air with characteristics separate from surroundings

Sleet

Ice crystals that are falling from the clouds melt partially refreeze

Hail

raindrops get sucked into the warm updrafts & freezes → hail grows as it rises and falls within the storm → hail that is too heavy will fall to the ground in a cool downdraft

What determines the size of hail?

1. strength of updrafts

2. thickness of clouds

3. availability of supercooled droplets

Pressure

a force that is exerted on every surface due to the collisions of gas molecules

Pressure gradient

a difference of pressure across some region created by heating differences

Steep Pressure Gradient

a large and rapid change in air pressure over a short distance, resulting in strong winds

Weak Pressure Gradient

a small difference in air pressure over a large area, resulting in light winds and stable weather conditions

What forces affect the wind?

Pressure Gradient Force (PGF), the Coriolis Effect, and Centrifugal Force

Where does the Coriolis Effect deflect wind to in the Northern Hemisphere?

the right

Where does the Coriolis Effect deflect wind to in the Southern Hemisphere?

the left

Where is the Coriolis Effect weakest?

the equator

Where is the Coriolis Effect strongest?

the poles

The rate at which the temperature changes inside a rising (or descending) parcel of saturated air is called

the moist adiabatic lapse rat

The dry adiabatic rate is the rate at which

temperature changes in a rising or descending parcel of unsaturated air

The most latent heat would be released in a ____ parcel of ____ saturated air

rising, warm

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

11 degrees C per 1000 m

In a conditionally unstable atmosphere, the environmental lapse rate will be ____ than the moist adiabatic rate and ____ than the dry adiabatic rate

greater, less

A conditionally unstable atmosphere is ____ with respect to unsaturated air and ____ with respect to saturated air

stable, unstable

Which condition below would make a layer of air more unstable?

cooling the upper part of the layer

If the environmental lapse rate is less than the moist adiabatic rate, the atmosphere is

absolutely stable

When the environmental lapse rate decreases more rapidly with height than the dry adiabatic rate, the atmosphere is

absolutely unstable

An inversion represents an extremely stable atmosphere because air that rises into the inversion will eventually become ____ and ____ dense than the surrounding air

colder, more

Which cloud type would most likely form in absolutely stable air?

stratus

If you observe large raindrops hitting the ground, you could probably say that the cloud overhead was ____ and had ____ updrafts

thick, strong

When are infrared satellite images available?

24/hrs a day

When are visible satellite images available?

Only available during daylight hours

A raindrop which freezes before reaching the ground is called

sleet

The largest snowflakes would probably be observed in ____ air whose temperature is ____ freezing

moist, near

Ice nuclei may be:

all of these

You would use a wooden stick to measure rainfall in the

standard rain gauge

Mercury is used in barometers primarily because of which one of the following properties?

mercury has a high density