Have you ever just looked Have you ever just looked at clouds?at clouds?

Why do we have Why do we have clouds?clouds?

Why are there Why are there different different shapes?shapes?

What can they What can they tell us about the tell us about the weather?weather?

Understanding CloudsUnderstanding Clouds

Clouds form as Clouds form as warmwarm air is air is forced upwardforced upward

As the air is As the air is forced upward, forced upward, it it expandsexpands and and coolscools

Four mechanisms that can cause air to rise are orographic lifting, frontal wedging, convergence,

and localized convective lifting.

• Orographic lifting occurs when mountains act as barriers to the flow of air, forcing the air to

ascend.

Orographic Lifting

What causes air to rise?What causes air to rise?

Frontal Wedging• A front is the boundary between two adjoining

air masses having contrasting characteristics.

What causes air to rise?What causes air to rise?

What causes air to rise?What causes air to rise?

• Convergence is when air flows together and rises.

Convergence

• Localized convective lifting occurs where unequal surface heating causes pockets of air to

rise because of their buoyancy.

Localized Convective Lifting

What causes air to rise?What causes air to rise?

Understanding CloudsUnderstanding Clouds

As the air cools, As the air cools, the relative the relative humidity humidity reaches 100%reaches 100%

HumidityHumidity and and RelativeRelative Humidity Humidity

HumidityHumidity is the amount of is the amount of water vapor in the airwater vapor in the air

Relative humidityRelative humidity is a measure is a measure of the amount of water vapor of the amount of water vapor that the air is holding, that the air is holding, compared to the amount it can compared to the amount it can hold at a specific temperaturehold at a specific temperature

HumidityHumidity and and RelativeRelative Humidity Humidity

When the air is holding as When the air is holding as much moisture as it can, it’s much moisture as it can, it’s said to be said to be saturatedsaturated

Can you explain this graph?Can you explain this graph?

Water vapor begins to condense Water vapor begins to condense in tiny drops around nuclei. in tiny drops around nuclei. Nuclei are small particles of Nuclei are small particles of dust, salt, and smoke in the dust, salt, and smoke in the

atmosphereatmosphere

Cloud TypesCloud Types Clouds are Clouds are

classified in classified in two two categories:categories:

ShapeShape, , HeightHeight, and , and sometimes sometimes RainRain CapacityCapacity

By Shape!By Shape! There are three main cloud There are three main cloud types that are based on shapetypes that are based on shape

Think you know any of them?Think you know any of them?

StratusStratus CumulusCumulus CirrusCirrus

Stratus CloudsStratus Clouds Stratus Stratus

clouds form clouds form a a smoothsmooth, , even sheeteven sheet

They usually They usually form at form at low low altitudesaltitudes

Cumulus CloudsCumulus Clouds These are These are

masses of masses of puffy, white puffy, white clouds, often clouds, often with flat baseswith flat bases

They form They form when air when air currents risecurrents rise

Cumulus CloudsCumulus Clouds They can be They can be

associated associated with both with both fair fair weather weather and and ThunderstormsThunderstorms, based on , based on their height.their height.

Cirrus CloudsCirrus Clouds Cirrus clouds Cirrus clouds

are high, thin, are high, thin, white, white, feathery feathery clouds clouds containing containing ice ice crystalscrystals

Cirrus CloudsCirrus Clouds Cirrus clouds Cirrus clouds

are usually are usually associated associated with fair with fair weather, but weather, but they may they may indicate indicate approaching approaching stormsstorms

By HeightBy Height The prefix of cloud names can The prefix of cloud names can

describe the height of cloud describe the height of cloud basesbases

Cirro:Cirro: High clouds above High clouds above 6000m6000m

By HeightBy Height

AltoAlto: Middle elevation clouds : Middle elevation clouds between between 2000 to 6000m2000 to 6000m

StratoStrato: Low level clouds below : Low level clouds below 2000m2000m

Rain CloudsRain Clouds NimbusNimbus

clouds are clouds are dark clouds dark clouds associated associated with with precipitationprecipitation

Rain CloudsRain Clouds When a nimbus When a nimbus

cloud is also a cloud is also a towering towering cumulus cloud, cumulus cloud, it’s called a it’s called a cumulonimbus cumulonimbus cloudcloud

Altocumulus Blue-gray, blanket-like Rain or snow likely Made of ice and water at middle heights

Cirrus Wispy ice clouds Seen in clear skies Mean good weather, but can mean a change in weather

Stratocumulus Dark, heavy water-droplet clouds

Rain or snow likely Seen at low or lower-middle heights

Cumulonimbus Giant thunderhead clouds

Thunderstorms with heavy rain

Hail, wind and lightening are on the way

Stratus Flat, low clouds Overcast skies Light rain, drizzle, or flurries likely

Cumulus Fluffy, lower clouds Fair weather Clouds can grow. If growing late in day, indicates change in weather

Name Appearance Conditions Facts

Ready for a quick review?Ready for a quick review?

1. Clouds can form when the 1. Clouds can form when the relative humidity reaches ____relative humidity reaches ____%%

2. In order for clouds to form, 2. In order for clouds to form, water vapor begins to water vapor begins to condense around ____of dust, condense around ____of dust, salt, and smokesalt, and smoke

3. Clouds are classified by ____ 3. Clouds are classified by ____ and____ and sometimes rain and____ and sometimes rain capacitycapacity

4. Puffy, white clouds are called?4. Puffy, white clouds are called? 5. Mid elevation clouds between 5. Mid elevation clouds between

2000 and 6000m2000 and 6000m

Let’s see how you did!Let’s see how you did!

1.1. 100100

2.2. NucleiNuclei

3.3. Shape and heightShape and height

4.4. CumulusCumulus

5.5. AltoAlto

Forms of Forms of PrecipitationPrecipitationPrecipitation (pre-sip-uh-Precipitation (pre-sip-uh-tay-shun) is any form of tay-shun) is any form of water that falls to the water that falls to the Earth's surfaceEarth's surface. .

Types of PrecipitationTypes of Precipitation

The type of precipitation that The type of precipitation that falls to the ground depends falls to the ground depends upon the formation process upon the formation process and the temperatures of the and the temperatures of the environment between the environment between the cloud and the surfacecloud and the surface

Can you name the Can you name the different types of different types of

precipitation?precipitation? RainRain SnowSnow HailHail SleetSleet

Freezing RainFreezing Rain

RainRain Rain develops when Rain develops when growing cloud droplets growing cloud droplets become too heavy to become too heavy to

remain in the cloud and remain in the cloud and as a result, fall toward the as a result, fall toward the

surface as rainsurface as rain

Rain can also Rain can also begin as ice begin as ice crystals that crystals that collect each collect each other to form other to form large large snowflakessnowflakes

As the falling As the falling snow passes snow passes through the through the freezing level freezing level into warmer into warmer air, the flakes air, the flakes melt melt

Rain from snow!Rain from snow!

SnowSnow

Snow is formed when ice Snow is formed when ice crystals form from water crystals form from water vapor that is in the clouds vapor that is in the clouds directly above your heads!directly above your heads!

This process is called This process is called sublimationsublimation

HailHail Hail is formed Hail is formed

when updrafts when updrafts carry raindrops carry raindrops upwards into upwards into extremely cold extremely cold areas of the areas of the atmosphereatmosphere

HailHail There the There the

raindrops raindrops merge and merge and freeze. When freeze. When the frozen the frozen clumps get to clumps get to heavy they fall heavy they fall to earthto earth

HailHail Hail can vary Hail can vary

in size, from in size, from the size of a the size of a small stone to small stone to that of a that of a baseball! baseball! So So be carefulbe careful

SleetSleet Sleet is frozen raindrops. Sleet is frozen raindrops.

Sleet begins as rain or snow Sleet begins as rain or snow and falls through a deep and falls through a deep layer of cold air that layer of cold air that contains temperatures contains temperatures below freezing that exist below freezing that exist near the surfacenear the surface..

SleetSleet Rain that falls Rain that falls

through this through this extremely extremely cold layer has cold layer has time to freeze time to freeze into small into small pieces of icepieces of ice

Freezing RainFreezing Rain Freezing rain is falling rain that Freezing rain is falling rain that

cools below 0°C, but does not cools below 0°C, but does not turn to ice in the air turn to ice in the air

The water is “The water is “supercooledsupercooled””

When the drops hit anything When the drops hit anything they instantly turn to ice!they instantly turn to ice!

HumidityHumidity and and RelativeRelative Humidity Humidity

HumidityHumidity is the amount of is the amount of water vapor in the airwater vapor in the air

Relative humidityRelative humidity is a measure is a measure of the amount of water vapor of the amount of water vapor that the air is holding, that the air is holding, compared to the amount it can compared to the amount it can hold at a specific temperaturehold at a specific temperature

HumidityHumidity and and RelativeRelative Humidity Humidity

When the air is holding as When the air is holding as much moisture as it can, it’s much moisture as it can, it’s said to be said to be saturatedsaturated

Can you explain this graph?Can you explain this graph?

In the cool of the morning, the In the cool of the morning, the air can’t hold as much air can’t hold as much moisture. We often have moisture. We often have dew dew on a summer morningon a summer morning

Once the air has warmed, the Once the air has warmed, the relative humidity drops since relative humidity drops since the air can hold more moisturethe air can hold more moisture