Weather

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 shapes?different shapes?

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

Take Good Notes!Take Good Notes!

There will be There will be a quiz on a quiz on this this informationinformation

Understanding CloudsUnderstanding Clouds Clouds form as Clouds form as

warm air is warm air is forced upwardforced upward

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

Fronts and Air MassesFronts and Air Masses An air mass is a large body of air An air mass is a large body of air whose temperature and moisture are whose temperature and moisture are

fairly similar at a given altitudefairly similar at a given altitude Fronts are boundaries separating Fronts are boundaries separating

different air massesdifferent air masses

There are four different air masses There are four different air masses that affect the United Statesthat affect the United States

The Air MassesThe Air Masses cPcP( continental polar) : cold, dry stable( continental polar) : cold, dry stable cTcT( continental tropical) : hot, dry, ( continental tropical) : hot, dry,

stable air aloft, unstable at the surfacestable air aloft, unstable at the surface mPmP( maritime polar) : cool, moist, ( maritime polar) : cool, moist,

unstableunstable mTmT( maritime tropical) : warm, moist, ( maritime tropical) : warm, moist,

unstableunstable

This map shows the air mass This map shows the air mass source regions and there pathssource regions and there paths

Ok, now we see the difference Ok, now we see the difference in the air massesin the air masses

Let’s look at the different fronts and their impact on Let’s look at the different fronts and their impact on weatherweather

Can you see the four different types of fronts on the Can you see the four different types of fronts on the map?map?

Warm FrontsWarm Fronts A warm front is A warm front is

warm air displacing warm air displacing cool air diagramcool air diagram

Shallow leading Shallow leading edge warm air edge warm air must “overrun” must “overrun” cold aircold air

These are usually These are usually slow movingslow moving

Cold FrontsCold Fronts Cold air advances into Cold air advances into

region of warm airregion of warm air Intensity of Intensity of

precipitation greater, precipitation greater, but short livedbut short lived

Clearing conditions Clearing conditions after front passesafter front passes

Usually approaches Usually approaches from W or NWfrom W or NW

Stationary FrontsStationary Fronts

Surface Surface positions of the positions of the front do not front do not movemove

Often a region Often a region of cloudsof clouds

Occluded FrontsOccluded Fronts Cold front Cold front

overtakes warm overtakes warm frontfront

Often found close Often found close to the low to the low pressure centerpressure center

Pressure’s AffectPressure’s Affect

L H L

CCloudslouds

CCondensesondenses

CCoolsools

EExpandsxpands

RRisesises

WWarm Airarm Air

W R E C C CW R E C C C

How Else Can Clouds Form?How Else Can Clouds Form? Fronts: When a Fronts: When a WARM FRONT RISES WARM FRONT RISES

OVER A COLD FRONTOVER A COLD FRONT. This produces non . This produces non violent rain showers.violent rain showers.

Fronts: When a Fronts: When a COLD FRONT RISES COLD FRONT RISES OVER A WARM FRONTOVER A WARM FRONT. This produces . This produces possibly violent rain storms very quickly, but possibly violent rain storms very quickly, but is brief and may last only part of the day.is brief and may last only part of the day.

Before Before ColdCold

Front Front

After After ColdCold

Front Front

Orographic Uplift: When air is forced up the Orographic Uplift: When air is forced up the side of a mountain or plateau. The air side of a mountain or plateau. The air forced up then cools down very quickly and forced up then cools down very quickly and condenses to form rain clouds.condenses to form rain clouds.

Understanding CloudsUnderstanding Clouds As the air cools, As the air cools,

the relative the relative humidity humidity reaches 100%reaches 100%

For more information on For more information on Relative Humidity click Relative Humidity click ☼☼

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

There are There are many many different different cloud typescloud types

Cloud TypesCloud Types Can you think Can you think

of the two of the two main ways main ways that clouds that clouds are classified?are classified?

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 smooth, a smooth, even sheeteven sheet

They usually They usually form at low form at low altitudesaltitudes

Stratus CloudsStratus Clouds When air is When air is

cooled and cooled and condenses near condenses near the ground, a the ground, a stratus cloud stratus cloud know as _______ know as _______ formsforms

Know the name?Know the name?

FogFog

Fog forms when a cold surface cools Fog forms when a cold surface cools the warmer moist air above it.the warmer moist air above it.

What is water vapor doing in the air to What is water vapor doing in the air to form fog?form fog?– CondenseCondense

At what temperature does the air hit to At what temperature does the air hit to condense as fog?condense as fog?– DewpointDewpoint

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 fair with both fair weather weather and…….when and…….when they get they get really tall!?!?!really tall!?!?!

Thunderstorms!Thunderstorms!

Cirrus CloudsCirrus Clouds Cirrus clouds Cirrus clouds

are high, thin, are high, thin, white, white, feathery feathery clouds clouds containing ice containing 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: High clouds above Cirro: High clouds above 6000m6000m

By HeightBy Height Alto: Middle elevation clouds Alto: Middle elevation clouds

between 2000 to 6000mbetween 2000 to 6000m

Strato: Low level clouds below Strato: Low level clouds below 2000m2000m

Rain CloudsRain Clouds Nimbus Nimbus

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

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 condense water vapor begins to condense around ____of dust, salt, and around ____of dust, salt, and smokesmoke

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. NucleiNuclei3.3. Shape and heightShape and height

4.4. CumulusCumulus5.5. 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!

1.1. Nuclei for the formation of rain Nuclei for the formation of rain drops can be small particles of: drops can be small particles of: A) salt, B) smoke, C) dust, D) all A) salt, B) smoke, C) dust, D) all the abovethe above

2.2. Which of these cloud types is not Which of these cloud types is not based on the clouds shape: A) based on the clouds shape: A) stratus, B) nimbus, C) cumulus, stratus, B) nimbus, C) cumulus, D) cirrusD) cirrus

33. . Mid elevation clouds between Mid elevation clouds between 2000 and 6000m: A) nimbus, 2000 and 6000m: A) nimbus, B) alto, C) cirro, D) stratoB) alto, C) cirro, D) strato

4. This form of precipitation is 4. This form of precipitation is supercooled: A) rain, B) snow, supercooled: A) rain, B) snow, C) sleet, D) freezing rainC) sleet, D) freezing rain

5.5. This form of precipitation This form of precipitation stays frozen all the way to the stays frozen all the way to the ground: A) rain, B) snow, C) ground: A) rain, B) snow, C) sleet, D) freezing rainsleet, D) freezing rain

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

The Answers!The Answers! 1. D1. D 2. B2. B 3. B3. B 4. D4. D 5. B5. B

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

You’ve seen water on the You’ve seen water on the outside of a cold drink?outside of a cold drink?

The cold air The cold air around the around the glass causes a glass causes a lower lower temperature at temperature at which the air is which the air is saturatedsaturated

You’ve seen water on the You’ve seen water on the outside of a cold drink?outside of a cold drink?

The The temperature temperature at which air is at which air is saturated and saturated and condensation condensation takes place is takes place is the the dew pointdew point

To return click To return click here here ☼☼