Cloud Development & Classification

Atmospheric CompositionAtmospheric CompositionAtmospheric Basics

Atmospheric CompositionAtmospheric Composition

Key Atmospheric GasesKey Atmospheric Gases

Atmospheric Basics

– The amount of water vapor in the The amount of water vapor in the atmosphere can be as much as four atmosphere can be as much as four percent of the atmosphere or as little as percent of the atmosphere or as little as almost zero. almost zero.

– Carbon dioxide, another variable gas, Carbon dioxide, another variable gas, makes up under one percent of the makes up under one percent of the atmosphere. atmosphere.

Temperature Versus HeatTemperature Versus Heat TemperatureTemperature is a measurement of how rapidly or is a measurement of how rapidly or

slowly molecules move. slowly molecules move.

State of the Atmosphere

HeatHeat the transfer of thermal energy from the transfer of thermal energy from one substance to another.one substance to another.

HeatHeat is the transfer of energy that fuels is the transfer of energy that fuels atmospheric processes, while atmospheric processes, while temperature temperature is used to measure and interpret that is used to measure and interpret that energy.energy.

Temperature Versus HeatTemperature Versus HeatMeasuring TemperatureMeasuring Temperature


– Temperature can be Temperature can be measured in degrees measured in degrees Fahrenheit (°F), in Fahrenheit (°F), in degrees Celsius (°C), degrees Celsius (°C), or in kelvins (K), the or in kelvins (K), the SI unit of temperature.SI unit of temperature.

– The Kelvin scale The Kelvin scale measures the number of measures the number of kelvins above absolute kelvins above absolute zero, a point where zero, a point where molecular motion molecular motion theoretically stops. theoretically stops.

Temperature Versus HeatTemperature Versus HeatDew PointDew Point


– The The dew pointdew point is the temperature to which air must be is the temperature to which air must be cooled in order for it to be saturated to trigger cooled in order for it to be saturated to trigger condensation.condensation.

a) Saturationa) Saturation is the point at which the air holds as much is the point at which the air holds as much water vapor as it possibly can. water vapor as it possibly can.

b) Condensation cannot occur until air is saturated.b) Condensation cannot occur until air is saturated.

– CondensationCondensation occurs when matter changes state occurs when matter changes state from a gas to a liquid. from a gas to a liquid.

Cloud Formation

Cloud FormationCloud Formation Buoyancy is the tendency for air to rise or sink Buoyancy is the tendency for air to rise or sink

as a result of differences in density.as a result of differences in density. There are There are 3 ways3 ways that clouds can form: that clouds can form:

Moisture in the Atmosphere

1) Clouds form when 1) Clouds form when warm, moist air rises, warm, moist air rises, expands, and coolsexpands, and cools in a in a convectionconvection current. current.

CondensationCondensation nucleinuclei are are smallsmall particlesparticles in the in the atmosphere around atmosphere around which cloud droplets which cloud droplets can form. can form.

Cloud FormationCloud Formation2) Orographic lifting2) Orographic lifting occurs when wind encounters a occurs when wind encounters a

mountainmountain and the air has no place to go but and the air has no place to go but upup. .


The air The air expandsexpands and cools resulting in and cools resulting in cloudcloud formationformation..

Cloud FormationCloud Formation3) Cloud formation occurs with the 3) Cloud formation occurs with the collisioncollision of of airair

massesmasses of of differentdifferent temperaturestemperatures. .


As warmer air collides with cooler air, the As warmer air collides with cooler air, the bulk of it will be forced to bulk of it will be forced to riserise overover the the more-dense, more-dense, coldcold air. air.

As the warm air As the warm air cools, the water cools, the water vapor in it vapor in it condensescondenses and and forms a cloud. forms a cloud.

Cloud FormationCloud FormationStabilityStability


– How rapidly any given mass of air cools determines How rapidly any given mass of air cools determines its stability.its stability.

– StabilityStability is the ability of an is the ability of an airair massmass to to resistresist risingrising. .

– The rate at which an air mass cools depends in part The rate at which an air mass cools depends in part on the on the temperaturetemperature of the surface of the surface beneathbeneath the air. the air.

– Air can become unstable if it is Air can become unstable if it is coolercooler than the surface than the surface beneath it. beneath it.

– If temperature conditions are right and the air mass If temperature conditions are right and the air mass rises rapidly, it can produce the type of clouds rises rapidly, it can produce the type of clouds associated with associated with thunderstorms.thunderstorms.

Cloud FormationCloud FormationLatent HeatLatent Heat


– As water vapor in the air condenses, As water vapor in the air condenses, heatheat is is released. released.

– The The energyenergy to to changechange liquidliquid water into a water into a gaseousgaseous state is stored in the state is stored in the waterwater vaporvapor..

– Latent heatLatent heat is is storedstored energyenergy in water vapor in water vapor that is not released to warm the atmosphere that is not released to warm the atmosphere until condensation takes place. until condensation takes place. ““Hidden – HeaHidden – Heatt””

– The amount of water vapor present in the The amount of water vapor present in the atmosphere is a significant source of energy atmosphere is a significant source of energy because of the latent heat it contains.because of the latent heat it contains.

Types of CloudsTypes of CloudsMoisture in the Atmosphere

The modern The modern system groups system groups clouds by the clouds by the altitudealtitude at which at which they form and by they form and by their their shapeshape..

– LowLow clouds typically clouds typically form below form below 20002000 m. m.

– MiddleMiddle clouds form between clouds form between 20002000 m to m to 60006000 m. m.

Altocumulus Lenticularis

– HighHigh clouds composed of clouds composed of iceice crystalscrystals form form above above 60006000 m. m.

The The halohalo around the sun or moon is a layer of around the sun or moon is a layer of cirruscirrus cloudsclouds made of ice crystals. These ice crystals act as made of ice crystals. These ice crystals act as tiny prisms, forming a white or sometimes colorful halo tiny prisms, forming a white or sometimes colorful halo around the sun or moon. This cirro-stratus cloud often around the sun or moon. This cirro-stratus cloud often indicates an approaching warm front and an indicates an approaching warm front and an associated area of low pressure. Rain or snow will not associated area of low pressure. Rain or snow will not always follow, but there is a higher probability of it always follow, but there is a higher probability of it after a halo is seen, and the brighter the circle, the after a halo is seen, and the brighter the circle, the greater the probability. greater the probability.

– VerticalVertical development clouds spread throughout development clouds spread throughout all altitudes at the all altitudes at the samesame timetime..

Types of CloudsTypes of CloudsMoisture in the Atmosphere

High clouds

Middle clouds

Low clouds

Wispy, feather-like, ice crystals.

Puffy, cotton-like,Fair weather clouds

Sheets, layers

Storm clouds

Types of CloudsTypes of Clouds

Types of Clouds 3:17 minutes

PrecipitationPrecipitation CoalescenceCoalescence occurs when cloud droplets occurs when cloud droplets collidecollide and and

joinjoin togethertogether to form a larger droplet. to form a larger droplet.


When the droplet becomes too heavy to be When the droplet becomes too heavy to be held aloft, gravity takes over and it held aloft, gravity takes over and it fallsfalls to to Earth Earth as as precipitationprecipitation. .

PrecipitationPrecipitation includes all forms of includes all forms of waterwater, , both liquid and solid, that fall from clouds both liquid and solid, that fall from clouds including including rain, snow, sleet, and hail.rain, snow, sleet, and hail.

PrecipitationPrecipitation When water vapor in the clouds becomes too heavy, it

can fall as rain, sleet, snow, or hail. Cloud droplets must first increase in size until gravity

pulls them down. If they pass through extremely cold layers of air, they

can freeze and produce sleet Snow is formed when water vapor changes directly

into a solid. Hail is formed when water droplets freeze in layers due

to updrafts and downdrafts.

The Water CycleThe Water Cycle At any one time, only a small percentage of At any one time, only a small percentage of

water is present in the atmosphere. water is present in the atmosphere.


The The water cyclewater cycle is the constant movement is the constant movement of water between the of water between the atmosphereatmosphere and and EarthEarth’’s s surfacesurface..

Water CycleWater Cycle

Exit Ticket (Write Question Exit Ticket (Write Question OutOut

1.1. Name the 5 atmospheric layers.Name the 5 atmospheric layers.2.2. Describe what the magnetosphere is.Describe what the magnetosphere is.3.3. What are the 3 ways that energy in the What are the 3 ways that energy in the

atmosphere can be transferred on atmosphere can be transferred on Earth?Earth?

4.4. How are clouds classified?How are clouds classified?5.5. What are the prefixes to describe What are the prefixes to describe

height: a) low b) middle c) high clouds?height: a) low b) middle c) high clouds?6.6. What are the prefixes to describe the What are the prefixes to describe the

shapes of clouds: a) wispy b) puffy c) shapes of clouds: a) wispy b) puffy c) layered d) stormlayered d) storm

Cloud Development & Classification

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