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%
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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
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