5/26 Cloud Formation

Front 1

An equilibrium is reached where the number of water molecules leaving the watersurface (rate of _______ ) is equal to the number of molecules returning to thesurface (rate of _______).

Back 1

evaporation, condensation

Front 2

The pressure (water content of the air) at thisequilibrium of evaporation and condensation is called the _________ ________ _______ .

Back 2

saturation vapor pressure

Front 3

“The maximum amount of water that can be held in a given volume of air”(called the saturation vapor pressure) is a function of ___ __________.

Back 3

air temperature

Front 4

Relative Humidity =

Back 4

Actual Vapor Pressure / Saturation Vapor Pressure X 100

Front 5

When relative humidity hits one hundred percent, that is the occasion on which we can record the _____ ______ temperature

Back 5

dew point

Front 6

______ _____: the decrease of an atmospheric variable with height, thevariable being temperature unless otherwise specified.(Change in temperature with altitude)

Back 6

Lapse rate

Front 7

What are the two types of lapse rate?

Back 7

Environmental lapse rate, Adiabatic lapse rates

Front 8

_______ _______ ______ – which refers to the actual change oftemperature with altitude for the stationary atmosphere (i.e. thetemperature gradient)

Back 8

Environmental lapse rate

Front 9

______ ______ _____ – which refer to the change in temperature of amass of air as it moves upwards.

Back 9

Adiabatic lapse rates

Front 10

There are two adiabatic rates:

Back 10

Dry adiabatic lapse rate

Moist (wet or saturated) adiabatic lapse rate

Front 11

The __________ ______ _____ , is the negative of the actual change of temperature withaltitude of the stationary atmosphere at a specific time and specific location.

Back 11

environmental lapse rate

Front 12

Theenvironmental lapse rate at a given place varies from day to day and even during eachday. T or F

Back 12

True

Front 13

As an average, the International Civil Aviation Organization (ICAO) defines an _______ _______ ______ (ISA) with a temperature lapse rate of _._°C/1,000 m(3.56 °F or 1.98 °C/1,000 ft) from sea level to __ km (36,090 ft).

Back 13

international standard atmosphere, 6.5, 11

Front 14

It is helpful to think of adiabatic processes as occurring within an air ____ .

Back 14

parcel

Front 15

By convention we think ofan air parcel as being a ___ _______ cubic meters in volume.

Back 15

few hundred

Front 16

The term adiabatic means that no ______ ______ (energy transfer due to a temperature difference)occurs into or out of the parcel. Air has low _______ conductivity, and the bodies of air involved are very large, so transfer of heat by conduction is negligibly small.

Back 16

heat transfer, thermal

Front 17

It is convenient to ignore mixing of surrounding air with the air parcel. The mixing of surroundingair with the air parcel is known as _________.

Back 17

entrainment

Front 18

The ____ ______ lapse rate is the negative of the rate at which a rising parcel of dry or unsaturatedair changes ________ with increasing height, under adiabatic conditions.

Back 18

dry adiabatic, temperature

Front 19

Unsaturated air has lessthan 100% relative humidity (its _______ is higher than its dew point).

Back 19

temperature

Front 20

When the air is stirred (for instance, by convection), and a parcel of air rises,it ______, because the pressure is lower at higher altitudes. As the air parcel ______, it pushes onthe air around it, doing work; since the parcel does work and gains no heat, it loses _______ ______,and so its temperature decreases at a rate of approximately 10.0 °C per 1,000 m

Back 20

expands, internal energy

Front 21

_____ ______ _____ is the altitude at which condensation begins (the temperatureof the rising air parcel reaches the dew point temperature).

Back 21

Lifting condensation level

Front 22

When an air parcel rises to the lifting condensation level, a critical thing happens. The ______ heat that was absorbed by the water vapor when it was evaporated is ______ upon reaching thelifting condensation level.

Back 22

latent, liberate

Front 23

while the air parcel will continue to rise past the lifting condensation level, it will not cool as rapidly as a dry air parcelbecause the ____ ______ of condensation is slowing the rate of adiabatic cooling.

Back 23

latent heat

Front 24

It's 5 degrees Celsius in Jan with 80% relative humdity, it's 30 degrees Celsius in July with 80% relative humidity. When does the day feel more humid, where is there a higher saturation rate?

Back 24

On the day in July because warmer air can hold more moisture

Front 25

When the air is saturated with water vapor (at its dew point), the _____ _____ lapse rate or ______ _____ lapse rate applies.

Back 25

moist adiabatic,saturated adiabatic

Front 26

Dry adiabatic rate = __.0 °C per 1,000 m

Moist adiabatic rate = __.0 °C per 1,000 m

Back 26

10, 5

Front 27

The reason for the difference between the dry and moist adiabatic lapse rates is that ______ ____ isreleased when water condenses.

Back 27

latent heat

Front 28

There are four mechanisms that cause air to rise:

Back 28

•Orographic Lifting

•Frontal Wedging

•Convergence

•Localized convective lifting

Front 29

When air is forced over a mountainous barrier, ______ lifting.

Back 29

Orographic

Front 30

When warmer, less dense air, is forced over cooler, denser air.

Back 30

Frontal Wedging

Front 31

When a pileup of horizontal air flow results in upward movement.

Back 31

Convergence

Front 32

When unequal surface heating causes localized pockets ofair to rise because of their buoyancy.

Back 32

Localized convective lifting

Front 33

As a parcel rises, it expands and cools (adiabatic). If we compare the air parcelto the surrounding air we can determine its ________ .

Back 33

stability

Front 34

If the air is cooler (more dense) than the surrounding air, then it is called _______ _____. _____ _____resists vertical movement.

Back 34

stable air

Front 35

If the air is warmer (less dense) than the surrounding air, then it is called____ ____. ______ _____ will rise (much like a hot-air balloon).

Back 35

Unstable air

Front 36

As dry air rises, itexpands and cools at the____ _____ lapse rate.Thus, it soon cools to thetemperature of thesurrounding air, and it _____ rising.

Back 36

dry adiabatic, stops

Front 37

As moist air rises, initially itcools at the ____ _____ lapserate. It soon cools to its _____ _____, and clouds form.

Back 37

dry adiabatic, dew point

Front 38

Air cools more slowly at the____ _____ lapse rate. As aresult, it remains warmer thansurrounding air and continuesto rise for thousands of meters.

Back 38

wet adiabatic

Front 39

Air stops rising when all_____ has condensed, andthe air again cools at its dryadiabatic rate.

Back 39

moisture

Front 40

Warm moist air is_______ because it rises rapidly, forming towering clouds and heavy rain. In addition, air rushes along the ground to replace the rising air, thus generating _____ ______ .

Back 40

unstable, surface winds

Front 41

Warm dry air is said to be _____ .

Back 41

stable

Front 42

______ _____ (L., wisp of hair) are high (6,000-15,000 m),wispy clouds composed of ice crystals rather than waterdroplets. High winds aloft blow them out into long, gentlycurved streamers.

Back 42

Cirrus clouds

Front 43

_______ (L., layer) are horizontally layered, sheet-likeclouds.

Back 43

Stratus clouds

Front 44

Stratus clouds form when _____________ forms at the sameelevation at which air stops rising, and the clouds spread outinto a broad sheet.

Back 44

condensation

Front 45

_______ _______ (L., heap or pile) are fluffy white cloudsthat typically display the flat bottoms and billowy tops.

Back 45

Cumulus clouds

Front 46

Thebase of a cumulus cloud forms at the altitude at which the rising aircools to its ____ ______ and condensation starts. However, itthis situation, the rising air remains ______ than thesurrounding air and therefore continues to rise, As it rises,more vapor _____, forming the billowing columns.

Back 46

dew point, warmer, condenses

Front 47

: sheet-like cloudswith some vertical structure

Back 47

stratocummulus

Front 48

: refers to clouds thatprecipitate

Back 48

nimbo

Front 49

: towering rain cloudthat produces intense rain, thunderand lightning

Back 49

cumulonimbus

Front 50

: stratus cloud fromwhich rain or snow falls

Back 50

nimbostratus

Front 51

: high stratus clouds

Back 51

altostratus

Front 52

: cloud that forms very close to the ground.

Back 52

Fog

Front 53

: created when warm, moist air from the sea blows onto cooler land surface.

Back 53

Advection fog

Front 54

: created when air near the surface cools by heat loss (radiation) at night.

Back 54

Radiation fog

Front 55

: created when air is cooled by evaporation from a body of water.

Back 55

Evaporation fog

Front 56

: created by rising airmass along a land surface.

Back 56

Upslope fog

Front 57

When condensation occurs above the ground, particulate matter, known as ________ _______, serve as surfaces for water vapor condensation (microscopic dust, smoke, saltparticles, etc.)

Back 57

condensation nuclei

Front 58

If the droplets that form are small, they require a long time to descend and may wellevaporate in the still air during descent.If the droplets coalesce they form large droplets and fall as _____.

Back 58

drizzle

Front 59

In many clouds, ice crystals form and grow as more water condenses on the surface. Asthey become large enough they fall and melt on descent, creating ______ .

Back 59

rainfall

Front 60

If temperatures at the surface are sufficiently low, the ice crystals remain frozen and fall as _____ .

Back 60

snow

Front 61

If falling ice crystals melt, but fall through a cold layer during descent, they may refreeze and create _____ . The sleet can refreeze on cold surfaces creating _____.

Back 61

sleet, gaze

Front 62

If turbulent winds exist in the ___ atmosphere, the falling ice crystals are transportedback upward into the cloud, where new layers of ice accumulate as additional vaporcondenses on their surface. The result is ____ (concentric shells of ice).

Back 62

hail

Front 63

Temperature ______ are not the common state of the lower atmosphere. Usually, air temperature decreaseswith an increase in altitude in the troposphere

Back 63

inversions

Front 64

In the mid-______, we often find temperature inversionsdeveloping along the moving ____ edge of a cold air mass that is overtaking warmer air.

Back 64

latitudes, front

Front 65

An inversion is also produced whenever _______ from the surface of the earth exceeds the amount of _______ received from the sun, which commonly occurs at night, or during the winter when the angle of the sun is verylow in the sky.

Back 65

radiation

Front 66

As snow falls into the layer of air where thetemperature is above freezing, the snowflakes partially melt. As the precipitationreenters the air that is below freezing, theprecipitation will re-freeze into ice pelletsthat bounce off the ground, commonlycalled _____ .

Back 66

sleet

Front 67

________ ________ will occur if the warm layer inthe atmosphere is deep with only a shallowlayer of below freezing air at the surface.

Back 67

Freezing rain

Front 68

_____ is frozen precipitation produced by intense thunderstorms.

Back 68

Hail

Front 69

Formation of Hail. As the snowflakes fall, liquid water freezes onto them formingice pellets that will continue to grow as more and more droplets are accumulated. Upon reaching the bottom of the cloud, someof the ice pellets are carried by the ______ back up to the top of the storm.

Back 69

updraft