Clouds And The Atmosphere Flashcards

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1
Q

What is a cloud

A

A mass of water drops or ice crystals suspended in the atmosphere

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2
Q

When do clouds form

A

When the air is saturated and cannot hold any more water

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3
Q

What are the two ways clouds can form

A

The amount of water in the air has increased
The air is cooked to its dew point
(BOTH) until the air is unable to old any more water

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4
Q

How do cumuliform clouds form

A
  1. When air is heated locally the air parcels rise through the atmosphere.
  2. These parcels expand and cool.
    3.as cooling reaches due point, condensation begins and clouds form
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5
Q

What form of clouds do cumuliform take

A

Flat bases and considerable vertical development

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6
Q

What do cumuliform clouds look like

A

Fluffy clouds which are relatively low in the sky

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7
Q

How do Stratiform (layer) clouds form

A

1.Air moves horizontally across a cooler surface
2. Turbulence and this process forms these clouds

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8
Q

What do Stratiform clouds look like

A

Grey uniform later clouds in the mid level if the atmosphere

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9
Q

How do Wispy cirrus clouds form

A
  1. They form at a high altitude and consist of tiny ice crystals.
  2. Do not produce precipitation do have little influence on water cycle.
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10
Q

What do Cirrus clouds look like

A

Wispy high up clouds.

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11
Q

Why are the suns rays not evenly spread around the world

A

Solar radiation travels longer distance through the atmosphere to get to the poles of the earth but a shorter distance to the equator

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12
Q

How do clouds help with weather predictions

A

Clouds help metereologists to predict the weather

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13
Q

How do clouds help with water distribution

A

Clouds help to move water across the planet

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14
Q

How do clouds help with planetary heat regulation

A

1 - cloud systems help spread the sun’s energy thats concentrated in tropics to the poles.
2 - some clouds contribute to warming because they trap heat.
3 - some clouds contribute to warming because they trap heat

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15
Q

What are the conditions needed for clouds to form and precipitation

A

1 - Water vapour enters the atmosphere through evaporation and wind transports it through advection
2 - aerosols come from volcanoes,forest fires, air pollution

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16
Q

What happens when water vapour and aerosols connect

A

The parcels become saturated and cool to their dew point till droplets begin to form and when they are large enough they fall

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17
Q

What must occur for clouds to form

A

Evaporation

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18
Q

What must be there for evaporation to occur

A

Heat (energy)

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19
Q

What is the heat energy used for in evaporation

A

The energy is used to break the binds that hold water molecules together

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20
Q

What happens when there are higher temperatures

A

There is more energy available to break bonds during evaporation

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21
Q

What percentage of moisture in the atmosphere is from evaporation

A

90%

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22
Q

What percentage of moisture in the atmosphere is from transpiration

A

10%

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23
Q

Where does frontal rain usually occur

A

In regions where warm tropical air meets cold polar air (usually mid lstitude)

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24
Q

How does frontal rain form

A

1 - when the two air masses meet the warm less dense air is lifted up and over the cold dense air
2 - warm lese dense air cools and water vapour condenses or falls as raindrops.

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25
Q

Where is the heaviest rainfall in frontal rain

A

Is on the front there can be rain before the front

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26
Q

How long can frontal rain system be

A

From hundred possibly thousands of miles long

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27
Q

Is frontal rain a small or large scale system

A

Large scale system

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28
Q

How does Orographic rain form

A

1 - moisture laden air is forced upwards over right ground producing cloud and potentially precipitation.
2 - precipitation on high ground removes moisture from the air creating a rain shadow and drier conditions on the leeward side

29
Q

What is it called when irographic and frontal rain are combined

A

The seeder feeder effect

30
Q

What does the seeder feeder effect cause

A

10x more rainfall on high ground than low ground areas

31
Q

Why do seeder clouds above feeder clouds cause more rain

A

The seeder clouds rain and washes out droplets in feeder clouds

32
Q

How do convective rain clouds form

A

1 - bubbles of air rising upwards in the atmosphere (happens when air is heated below)
2 - the bubbles cool and the water vapour it contains condenses into clouds
3 - when the cloud reaches a certain depth or the clouds top temperature cool sufficiently it will rain

33
Q

What type of cloud produces convective rain

A

Cumulus cloud

34
Q

What type of atmospheres form convective clouds

A

Unstable atmospheres

35
Q

What type of cloud is convective rain

A

Short time rain and covers a small area

36
Q

How does snow form

A

1 - begins as ice crystals in high clouds below freezing (0°C).
2 - snowflakes form when ice crystals stick together as they fall through the cloud.

37
Q

How does snow stay as snow when it falls through the atmosphere

A

The snowflakes must stay frozen from cloud to surface so it must fall through cold air

38
Q

How does sleet form

A

1 - begins as ice crystals in high clouds below freezing (0°C)
2 - sleet is a mix if tain and snow formed when snow falls through a layer of warmer air near the ground
3 - some flakes melt whilst others remain as snow

39
Q

How does freezing rain form

A

1 - forms when raindrops hit surfaces that are below freezing (0°C)
2 - they freeze on impact and turn into ice

40
Q

How does freezing rain form

A

1 - forms when raindrops hit surfaces that are below freezing (0°C)
2 - they freeze on impact and turn into ice

41
Q

What are the 6 air masses called

A

Polar maritime mass
Returning polar maritime
Artic maritime mass
Polar continental air mass
Tropical continental air mass
Tropical maritime air mass

42
Q

Where is polar maritime air mass form and what is it like

A

From greenland/ Arctic sea
Wet cold air bringing cold showery weather

43
Q

Where is returning polar maritime form and what is it like

A

From greenland/ Arctic via North Atlantic
Moist mild and unstable air bringing cloud and rain showers

44
Q

Where is arctic maritime air mass form and what is it like

A

From Arctic
Wet cold air brings snow in winter

45
Q

Where is polar continental air mass form and what is it like

A

From central europe
Hot air brings dry summers cold air brings snow in winter

46
Q

Where is tropical continental air mass form and what is it like

A

From North Africa
Hot dry air brings hot weather in summer

47
Q

Where is tropical maritime air mass form and what is it like

A

From Atlantic
Warm moist air brings cloud rain and mild weather

48
Q

What is humidity

A

The humidity of an air mass is the concentration of water vapour present in air

49
Q

What are the two ways if measuring humidity

A

Absolute
Relative

50
Q

What is absolute humidity

A

A measure of actual water vapour in the air measured in (g/cm³)

51
Q

What is relative humidity

A

The ratio of absolute humidity to the theoretical maximum for a given temperature and lressure

52
Q

What is (g/cm³)

A

Grams if moisture per cubic meter of air

53
Q

Which air can hold more vapour warm or cold

A

Warmer air

54
Q

Which air take steps water vapour to become saturated

A

Colder air

55
Q

If the temperature 30°C whats the maximum water that a parcel can hold

A

30g/m³

56
Q

If a parcel of air is filled with water vapour what is it

A

Saturated so condensation can occur and clouds can form

57
Q

What is relative humidity

A

The amount if water vapour as a % of what a parcel could hold

58
Q

If a water droplet has only 50% relative humidity what does it mean

A

It means it is only storing 50% of what it could store. To become saturated it needs to get 100% relative humidity then it becomes saturated and condenses to form a cloud

59
Q

What happens when air reaches 100% humidity

A
  • the air is now saturated and has reached its dew point/ condensation level
  • water condenses from water vapour gas (energy known as latent heat is released as part of this process) and clouds for.
60
Q

What are the 3 lapse rates called

A

Environmental lapse rate (ELR)
Dry adiabatic lapse rate (DLAR)
Saturated adiabatic lapse rate (SALR)

61
Q

What is the environmental lapse rate (ELR)

A

The rate if decrease of temperature with altitude in the stationary atmosphere at a given time and location. AVERAGE: -6.5°C for -100m

62
Q

What is the dry adiabatic lapse rate (DALR)

A

The rate at which a parcel of dry air (less than 100% humidity) cools. The DALR (rate at which rising air cools) is ~ 10°C per 1000m

63
Q

What is the saturated adiabatic lapse rate (SALR)

A

The rate at which a saturated parcel of air cools as it rises through the atmosphere because condensation releases latent heat. The SALR is 7°C/km

64
Q

How is an atmosphere stable

A

Air that is cooler than the atmospheric air will sink to the Earths surface as it does it warms and doesn’t form clouds leading to: high pressure, atmospheric stability

65
Q

Is atmospheric stability relate to high or low pressure sytems

A

High pressure

66
Q

What are the typical conditions of atmospheric stability

A

Dry weather and mostly clear skies with larger diurnal temperature changes due to greater radiation loss at night and greater sunshine during the day

67
Q

What is atmospheric instability

A

When air that is warmer than the atmospheric air rises to a level where it reaches its dew point (100% humidity) water condenses and forms clouds which leads to: low pressure, atmospheric instability

68
Q

Does atmospheric instability relate to high or low pressure systems

A

Low pressure

69
Q

What are the typical conditions in an instable atmosphere

A

Clouds and precipitation that minimise temperature changes throughout the day