Weather/Meteorology

Weather/MeteorologyWeather/Meteorology

Atmosphere and Heat Energy Video Atmosphere and Heat Energy Video ClipClip

The AtmosphereThe Atmosphere

99%99% of the atmosphere is of the atmosphere is nitrogennitrogen and and oxygenoxygen..

The remaining 1% is The remaining 1% is smallsmall amounts of amounts of argon, hydrogen, carbon dioxide, and argon, hydrogen, carbon dioxide, and waterwater vaporvapor..

ESRT ALERT!!ESRT ALERT!! – page – page 11 gives you this gives you this information for free!!information for free!!


The amount of nitrogen and oxygen needs to stay The amount of nitrogen and oxygen needs to stay fixedfixed, or we would be in trouble., or we would be in trouble.

However, the amount of However, the amount of water vaporwater vapor is constantly is constantly changingchanging…that’s one reason we have …that’s one reason we have weatherweather!!

There are 4 main layers to the atmosphere:There are 4 main layers to the atmosphere: 1. Troposphere1. Troposphere 2. Stratosphere2. Stratosphere 3. Mesosphere3. Mesosphere 4. Thermosphere4. Thermosphere


The The tropospheretroposphere is the only layer that contains is the only layer that contains water vaporwater vapor, thus it is the ONLY layer that has any , thus it is the ONLY layer that has any weatherweather!!

This is This is why pilotswhy pilots sometimes say they are “flying sometimes say they are “flying above the weather” to avoid a storm. They are above the weather” to avoid a storm. They are flying flying aboveabove the the TroposphereTroposphere!!

ESRT ALERT!!ESRT ALERT!! – Top of page – Top of page 1414 has a chart that has a chart that shows you all you need to know about the layers shows you all you need to know about the layers of the atmosphere! – of the atmosphere! – YES, this means to go YES, this means to go there now in your ESRT!!!there now in your ESRT!!!

Using page 14 of the ESRTUsing page 14 of the ESRT

What can we say about the temperature in What can we say about the temperature in eacheach of of the layers of the atmosphere?the layers of the atmosphere?

It’s VARIABLE – goes up and down inconsistentlyIt’s VARIABLE – goes up and down inconsistently What can we say about pressure in What can we say about pressure in eacheach of the of the

layers of the atmosphere?layers of the atmosphere? Steadily decreases the higher you go in the Steadily decreases the higher you go in the

atmosphereatmosphere.. WhyWhy does it decrease? does it decrease? Because the higher you go, the less atmosphere is Because the higher you go, the less atmosphere is

above you so there’s less pressure pushing down above you so there’s less pressure pushing down on youon you..

Ozone Layer Video ClipOzone Layer Video Clip

The Ozone LayerThe Ozone Layer

OzoneOzone (O3) is another important component of the (O3) is another important component of the atmosphereatmosphere..

It is formed when a It is formed when a thirdthird oxygen atom (O) oxygen atom (O) combines with an combines with an oxygen moleculeoxygen molecule (O2). (O2).

This layer of the atmosphere protects us from This layer of the atmosphere protects us from harmful harmful ultraviolet lightultraviolet light..

Each time chlorofluorocarbons (Cfc’s) are Each time chlorofluorocarbons (Cfc’s) are released into the atmosphere, they literally released into the atmosphere, they literally pull pull apartapart one oxygen atom from the O3, turning it one oxygen atom from the O3, turning it back into O2.back into O2.

This has caused massive This has caused massive holesholes in the ozone layer. in the ozone layer.

NASA.gov Ozone Hole Watch

Before CFCs were banned, they were used in aerosols, refrigerators, air conditioners in homes, vehicles and businesses, fire extinguishers, insulating foams, styrofoam food packaging, and cleaning and electronic solvents.

http://ozonewatch.gsfc.nasa.gov/

http://ozonewatch.gsfc.nasa.gov/

http://earth.rice.edu/mtpe/atmo/atmosphere/topics/ozone/Ozone_Causes.mov

Solar EnergySolar Energy

The The sunsun delivers delivers heatheat energy to Earth’s energy to Earth’s surface.surface.

This is called This is called radiationradiation.. This heat energy is This heat energy is absorbedabsorbed and also and also

radiated back into space.radiated back into space. The The physicalphysical characteristics of Earth’s characteristics of Earth’s

surface affect how surface affect how muchmuch heat energy is heat energy is absorbed.absorbed.

Solar EnergySolar Energy

Color:Color: The The darkerdarker an object, the an object, the moremore heat it absorbs. heat it absorbs. Texture:Texture: The The rougherrougher an object, the an object, the moremore heat it absorbs. heat it absorbs. Therefore, Therefore, dark and roughdark and rough objects (like rocks, objects (like rocks,

mountains) absorb the most heat.mountains) absorb the most heat. Light and smoothLight and smooth objects (like water and snow) do objects (like water and snow) do

not absorb much at all. Instead, they not absorb much at all. Instead, they reflectreflect heat. heat.

Specific HeatSpecific Heat

The The specific heatspecific heat of a substance is its resistance of a substance is its resistance to to heatingheating up or up or coolingcooling off. off.

If something’s specific heat is If something’s specific heat is highhigh, it takes a , it takes a longlong time to heat up, but will time to heat up, but will keepkeep the heat for a long the heat for a long time.time.

If something’s specific heat is If something’s specific heat is lowlow, it will heat up , it will heat up quicklyquickly, but also , but also loselose the heat quickly. the heat quickly.

ESRT ALERT!!ESRT ALERT!! – Page – Page 11 contains a chart with the contains a chart with the specific heats of some common materials.specific heats of some common materials.

Water has a very high specific heat – takes a long time to heat water up, but once it’s warm it stays warm for a long time.

Metals, like lead and copper have low specific heats – they will heat up very quickly, but cool down very fast too.

Energy TransferEnergy Transfer

Energy in the atmosphere and at Earth’s surface is Energy in the atmosphere and at Earth’s surface is transferredtransferred in two main ways:in two main ways:

1. 1. ConductionConduction is the transfer of energy when is the transfer of energy when molecules molecules collidecollide, or actually come in contact with , or actually come in contact with each other.each other.

2. 2. ConvectionConvection is the transfer of energy is the transfer of energy throughthrough a a substance. It is a substance. It is a circularcircular motion!! motion!!– Warm air risesWarm air rises (due to low density), it then (due to low density), it then expands and expands and

coolscools (density is now high), so the air then (density is now high), so the air then sinkssinks back back down. This occurs over and over again.down. This occurs over and over again.

Energy TransferEnergy Transfer Think of a pot of boiling Think of a pot of boiling

water.water. ConductionConduction is going on is going on

when the flame comes in when the flame comes in contactcontact with the pan and with the pan and heats it up.heats it up.

Then Then convectionconvection occurs occurs withinwithin the water itself the water itself allowing all the water allowing all the water molecules to heat up and molecules to heat up and begin to boil.begin to boil.

http://ethel.as.arizona.edu/~collins/astro/navigation.html

Convection

Conduction

ESRT ALERT!! - Page 1 – Energy Properties of Water

Cause of WeatherCause of Weather

MeteorologyMeteorology is the study of atmospheric is the study of atmospheric phenomena.phenomena.

For example:For example: cloudsclouds, raindrops, , raindrops, snowflakessnowflakes, fog, , fog, dust, and rainbows.dust, and rainbows.

The The currentcurrent state of the atmosphere is considered state of the atmosphere is considered weatherweather..

Weather is a Weather is a short-termshort-term thing and can occur in thing and can occur in small areas!!!small areas!!!

On the other hand, On the other hand, climatesclimates are are long-termlong-term and and cover entire areas.cover entire areas.

Causes of WeatherCauses of Weather

The main The main causecause of weather is due to an imbalance of weather is due to an imbalance of the of the sun’s rayssun’s rays hitting the Earth. hitting the Earth.

The sun’s rays The sun’s rays DO NOTDO NOT hit all spots on the Earth hit all spots on the Earth with the same with the same intensityintensity..

Higher latitudesHigher latitudes (above Tropics of Cancer and (above Tropics of Cancer and Capricorn) have Capricorn) have low intensitylow intensity sun’s rays. sun’s rays.

Lower latitudesLower latitudes (between Tropics of Cancer and (between Tropics of Cancer and Capricorn) have Capricorn) have high intensityhigh intensity sun’s rays. sun’s rays.

It all has to do with the It all has to do with the angleangle of the sun’s rays!! of the sun’s rays!!

Causes of WeatherCauses of Weather

This This differencedifference of the sun’s rays causes of the sun’s rays causes heat energy to constantly be heat energy to constantly be redistributedredistributed, , mostly through mostly through convectionconvection..

Everything then gets brought into Everything then gets brought into balancebalance once the energy gets redistributed.once the energy gets redistributed.

This entire process creates This entire process creates weatherweather!!!!

Temperature Contrasts Video ClipTemperature Contrasts Video Clip

TemperatureTemperature

TemperatureTemperature and heat are and heat are NOTNOT the same the same thing!thing!

HeatHeat is an actual is an actual energyenergy that’s transferred.that’s transferred. Temperature is a Temperature is a measurementmeasurement of that of that

energy.energy. Let’s remind ourselves of the Let’s remind ourselves of the relationshiprelationship

between between temperaturetemperature and and densitydensity and and temperature and temperature and pressurepressure..

TemperatureTemperature

As As temperature increasestemperature increases, , density decreasesdensity decreases and and vice-versa.vice-versa.

As As temperature increasestemperature increases, , atmospheric pressure atmospheric pressure decreasesdecreases, and vice-versa., and vice-versa.

Keep these in mind in the next few weeks, these Keep these in mind in the next few weeks, these are VERY important relationships in weather!are VERY important relationships in weather!

ESRT ALERT!!ESRT ALERT!! – Remember on page – Remember on page 1313 you will you will find a temperature conversion scale that will be find a temperature conversion scale that will be very useful! Also, there is a pressure conversion very useful! Also, there is a pressure conversion scale.scale.

Relative Humidity Video ClipRelative Humidity Video Clip

Dew Point and Relative HumidityDew Point and Relative Humidity

The The dew pointdew point is the is the temperaturetemperature that air needs to that air needs to be be cooledcooled to in order to be to in order to be saturatedsaturated (completely (completely full of water).full of water).

When you leave a glass of When you leave a glass of ice waterice water out on a out on a hot hot dayday, the air right around the glass gets cooled to , the air right around the glass gets cooled to its its dew pointdew point and forms “dew” or and forms “dew” or condensationcondensation..

The The relative humidityrelative humidity is a is a RATIORATIO of the actual of the actual amount of water in the air compared to how much amount of water in the air compared to how much it it COULDCOULD hold. hold.


WarmWarm air can hold air can hold more moisturemore moisture than than coldcold air air can!!can!!

Therefore, typically we FEEL Therefore, typically we FEEL humidityhumidity more on more on warmwarm days because the air is able to days because the air is able to hold morehold more moisture thus it’s filled with more moisture.moisture thus it’s filled with more moisture.

On a On a cold daycold day, it is more likely to , it is more likely to snow or rainsnow or rain because the air because the air can’t really holdcan’t really hold much moisture so much moisture so the moisture falls out of the air in the form of the moisture falls out of the air in the form of precipitationprecipitation..


Let’s put the two together!Let’s put the two together! If dew point is the temperature it needs to be for If dew point is the temperature it needs to be for

air to be completely full of water, and relative air to be completely full of water, and relative humidity is the ratio of what’s there compared to humidity is the ratio of what’s there compared to what could be there, then what does it mean when what could be there, then what does it mean when the dew point and the actual temperature (dry the dew point and the actual temperature (dry bulb) are the same number?bulb) are the same number?

It means the air is 100% full of water and that It means the air is 100% full of water and that means that the relative humidity is 100%. means that the relative humidity is 100%. Weather is very wet – probably raining!Weather is very wet – probably raining!


OK, so what does it mean when the dew point and OK, so what does it mean when the dew point and the actual temperature are just close together but the actual temperature are just close together but NOT the same number?NOT the same number?

It means that the relative humidity is high, but not It means that the relative humidity is high, but not 100%. Weather is probably not that nice and feels 100%. Weather is probably not that nice and feels humid.humid.

What about if the dew point and actual What about if the dew point and actual temperature are very far apart?temperature are very far apart?

It means the relative humidity that day is very low. It means the relative humidity that day is very low. Weather is clear and not humid!Weather is clear and not humid!

Dew Point and Relative HumidityDew Point and Relative Humidity The The instrumentinstrument used to measure dew points used to measure dew points

and relative humidity is a and relative humidity is a sling psychrometersling psychrometer..


Using a sling psychrometer, you obtain the Using a sling psychrometer, you obtain the actual temperature outside actual temperature outside (dry bulb)(dry bulb) and a and a wet bulbwet bulb temperature. temperature.

With these With these twotwo numbers and either a dew numbers and either a dew point or relative humidity point or relative humidity chartchart, you can , you can figure out the dew point or relative humidity.figure out the dew point or relative humidity.

ESRT ALERT!!ESRT ALERT!! – Page – Page 1212 contains both a contains both a dew point and relative humidity chart. Let’s dew point and relative humidity chart. Let’s learn how to use them!learn how to use them!


All you need is the All you need is the dry bulbdry bulb number and the wet number and the wet bulb number.bulb number.

STEP ONE is to STEP ONE is to SUBTRACTSUBTRACT those 2 numbers!!! those 2 numbers!!! Whatever you get when you subtract those 2 Whatever you get when you subtract those 2

numbers is the number you use at the numbers is the number you use at the toptop of the of the chart.chart.

Then just use the given dry bulb number for the Then just use the given dry bulb number for the left sideleft side of the chart and where they meet is your of the chart and where they meet is your answer!! answer!!

Let’s try it!Let’s try it!

Dew Point and Relative HumidityDew Point and Relative Humidity The dry bulb temperature is 20 The dry bulb temperature is 20 ºC and the wet bulb ºC and the wet bulb

temperature is 16 ºC. What is the dew point?temperature is 16 ºC. What is the dew point? 20 – 16 = 420 – 16 = 4 Use the dew point chart and find Use the dew point chart and find 44 at the top and at the top and 2020 on on

the left and you end up with the left and you end up with 14 ºC14 ºC as your answer! as your answer! Now, use the same dry bulb and wet bulb, but find the Now, use the same dry bulb and wet bulb, but find the

relative humidity.relative humidity. 20 – 16 = 420 – 16 = 4 Use the relative humidity chart and find Use the relative humidity chart and find 44 at the top at the top

and and 2020 on the left and you end up with on the left and you end up with 66%66% as you as you answer!answer!

Air Pressure Video ClipAir Pressure Video Clip

Wind and Air PressureWind and Air Pressure

The only reason we have The only reason we have windwind is due to is due to airair pressurepressure differences on Earth. differences on Earth.

When air When air warmswarms, the , the pressure dropspressure drops.. When air When air coolscools, the , the pressure risespressure rises.. Air likes to Air likes to movemove from high pressure to low from high pressure to low

pressure.pressure. AIR GO, HIGH LOWAIR GO, HIGH LOW Therefore, we would never have wind if it weren’t Therefore, we would never have wind if it weren’t

for for pressure differencespressure differences..

Wind Video ClipWind Video Clip


Wind is named for the direction its Wind is named for the direction its COMINGCOMING FROMFROM, , NOTNOT the direction its going to. the direction its going to.

Therefore, a Therefore, a northeastnortheast wind means its wind means its coming from the northeast and moving coming from the northeast and moving towards the towards the southwestsouthwest..

Example: Wind speed = 12 mph, Wind Example: Wind speed = 12 mph, Wind direction = SEdirection = SE

This means the wind is moving at 12 mph This means the wind is moving at 12 mph FROMFROM the the southeastsoutheast..


When a When a high pressurehigh pressure system system develops, air moves develops, air moves outwardoutward from the from the high pressure area and high pressure area and clockwiseclockwise..

When a When a low pressurelow pressure system system develops air moves develops air moves inwardinward to the low to the low pressure area and pressure area and counterclockwise.counterclockwise.


Air pressure is measured using a Air pressure is measured using a barometerbarometer.. The units are either The units are either millibarsmillibars (metric) or (metric) or inches of inches of

mercurymercury (English).(English). Lines that connect Lines that connect equalequal air pressure on a weather air pressure on a weather

map are called map are called isobarsisobars.. The The closercloser the isobars are to each other, the the isobars are to each other, the

higherhigher the wind speed. the wind speed. ESRT ALERT!!ESRT ALERT!! – Remember, page – Remember, page 1313 has a has a

pressure conversion chart which will be helpful. pressure conversion chart which will be helpful.

Windy!!

Not so windy!!

Land and Sea BreezesLand and Sea Breezes

Since wind is created when there’s pressure Since wind is created when there’s pressure differences, two typical types of breezes differences, two typical types of breezes occur:occur:

1. A land breeze1. A land breeze 2. A sea breeze2. A sea breeze


A A sea breezesea breeze occurs in the occurs in the daytimedaytime. During the . During the day day waterwater is generally is generally coolercooler than the than the landland. Water . Water has a has a highhigh specific heat so it takes a while to warm specific heat so it takes a while to warm up. Land has a up. Land has a lowlow specific heat and heats up specific heat and heats up really quick. really quick.

Because of this, there is a Because of this, there is a high pressurehigh pressure over the over the water and a water and a low pressurelow pressure over the land. Since air over the land. Since air likes to go from high to low, a constant breeze likes to go from high to low, a constant breeze flows flows FROMFROM the the water towards the landwater towards the land..

You’ve probably felt this at the beach before.You’ve probably felt this at the beach before.


A A land breezeland breeze occurs at occurs at nightnight. Now, the . Now, the land has land has cooledcooled down due to its low specific down due to its low specific heat, but because water has a high specific heat, but because water has a high specific heat it’s heat it’s warmerwarmer than the land. than the land.

This creates a This creates a low pressurelow pressure over the water over the water and a and a high pressurehigh pressure over the land. over the land.

The air moves The air moves FROMFROM the land towards the the land towards the water.water. Land and sea breeze animation

http://www.classzone.com/books/earth_science/terc/content/visualizations/es1903/es1903page01.cfm?chapter_no=visualization

Air Masses Video ClipAir Masses Video Clip

Air MassesAir Masses

An An air massair mass is a large body of air that takes is a large body of air that takes on the on the characteristicscharacteristics of the area over which of the area over which it it formedformed..

There are 2 main ways to classify air There are 2 main ways to classify air masses:masses:

1. Those that form over 1. Those that form over landland are are drydry. We . We call these call these continental (c)continental (c) air masses. air masses.

2. Those that form over 2. Those that form over waterwater are are moistmoist. . We call these We call these maritime (m)maritime (m) air masses. air masses.

Air Masses Cont.Air Masses Cont.

Water Air MassesWater Air Masses


Once it is determined if it’s a continental air Once it is determined if it’s a continental air mass or a maritime air mass, there are 3 mass or a maritime air mass, there are 3 different different temperaturetemperature classifications: classifications:

1. Tropical (T) = warm 1. Tropical (T) = warm 2. Polar (P) = cold2. Polar (P) = cold 3. Arctic (A) = VERY cold3. Arctic (A) = VERY cold


Now, we can combine the “c” or “m” from the type Now, we can combine the “c” or “m” from the type of air mass and the “T”, “P”, or “A” from the of air mass and the “T”, “P”, or “A” from the temperature to create each type of air mass:temperature to create each type of air mass:

1. cT = 1. cT = continental tropicalcontinental tropical (dry and warm) (dry and warm) 2. cP = 2. cP = continental polarcontinental polar (dry and cold) (dry and cold) 3. cA = 3. cA = continental arcticcontinental arctic (dry and very cold) (dry and very cold) 4. mT = 4. mT = maritime tropicalmaritime tropical (moist and warm) (moist and warm) 5. mP = 5. mP = maritime polarmaritime polar (moist and cold) (moist and cold) There is no such thing as a mA air mass – it would There is no such thing as a mA air mass – it would

be be so coldso cold that the that the moisturemoisture would be would be frozenfrozen..


ESRT ALERT!!!ESRT ALERT!!! – – bottom of page bottom of page 1313 gives you the names gives you the names and symbols of these and symbols of these air masses for free!air masses for free!

HOWEVER, you still HOWEVER, you still have to have to memorizememorize what they mean!!what they mean!!

Global Winds Video ClipGlobal Winds Video Clip

Global WindsGlobal Winds

There are three basic wind zones on Earth.There are three basic wind zones on Earth. 1. The trade winds1. The trade winds 2. The prevailing westerlies2. The prevailing westerlies 3. The polar easterlies3. The polar easterlies


The The trade windstrade winds are found at are found at 3030º Nº N and and 30º30º SS latitude. latitude.

At these 2 places, At these 2 places, air sinksair sinks, warms up and , warms up and then moves then moves towardstowards the the equatorequator where it where it rises rises againagain..

This process is a This process is a convectionconvection current!! current!!

The sinking air from the north and south hemispheres converge at the equator and are forced upward. This creates a low pressure at the equator.

L


The The prevailing westerliesprevailing westerlies flow between flow between 3030ºº andand 6060ºº north and south latitude. north and south latitude.

We are located in this zone!We are located in this zone! Remember, wind is named for the direction Remember, wind is named for the direction

it it comescomes from. So, these winds are actually from. So, these winds are actually blowing towards the blowing towards the easteast..

**This is why weather moves from **This is why weather moves from west to west to easteast in the United States!! in the United States!!

These winds move towards the These winds move towards the polespoles..


The The polar easterliespolar easterlies are found between are found between 6060ºº north and south latitude and the north and south latitude and the north or north or south polessouth poles..

They are characterized by They are characterized by very cold airvery cold air..

Global WindsGlobal Winds ESRT ALERT!!ESRT ALERT!! – middle of – middle of

page page 1414 has a planetary has a planetary wind belt diagram!wind belt diagram!

Global winds animationGlobal winds animation

Barometer – measures air pressure

Anemometer – measures wind speed

The Coriolis EffectThe Coriolis Effect

Because the Earth Because the Earth rotatesrotates from from westwest to to easteast all all winds in the northern hemisphere blow winds in the northern hemisphere blow oppositeopposite the direction than the ones in the southern the direction than the ones in the southern hemisphere.hemisphere.

In addition, because it rotates, all winds on Earth In addition, because it rotates, all winds on Earth are slightly are slightly bentbent or or curvedcurved rather than strait. rather than strait.

This is called the This is called the Coriolis EffectCoriolis Effect.. Winds curve to the Winds curve to the rightright in the in the northernnorthern

hemisphere and to the hemisphere and to the leftleft in the in the southernsouthern hemisphere.hemisphere.

Coriolis effect animation

Coriolis effect video

Jet Stream Video ClipJet Stream Video Clip

The Jet StreamThe Jet Stream

The The jet streamjet stream is literally a is literally a riverriver of wind high of wind high in the atmosphere. in the atmosphere.

The jet streams can The jet streams can steersteer major air masses, major air masses, pressure systems, and pressure systems, and frontsfronts in certain in certain directions.directions.

There are two main jet streams in each There are two main jet streams in each hemispherehemisphere..

A A subtropicalsubtropical jet stream and a jet stream and a polarpolar jet jet stream.stream.

Jet Stream animation

Fronts Video ClipFronts Video Clip

FrontsFronts

Sometimes air masses can Sometimes air masses can collidecollide with each other. with each other. This will form a This will form a frontfront.. A front is a A front is a narrownarrow region region separatingseparating two air two air

masses of different densities.masses of different densities. There are four types of fronts:There are four types of fronts: 1. Cold front1. Cold front 2. Warm front2. Warm front 3. Stationary front3. Stationary front 4. Occluded front4. Occluded front

FrontsFronts

Cold Fronts:Cold Fronts: In a cold front ,cold In a cold front ,cold densedense air will air will displacedisplace (push (push

away) warm air and force the warm air away) warm air and force the warm air upwards.upwards. Type of weather associated with this type of front Type of weather associated with this type of front

is clouds, rain, and is clouds, rain, and thunderstormsthunderstorms.. The symbol on a weather map is a The symbol on a weather map is a blue lineblue line with with

blue blue trianglestriangles that that pointpoint in the direction of the cold in the direction of the cold air movement.air movement.

Often form cumulus or cumulonimbus clouds Often form cumulus or cumulonimbus clouds (high, fluffy/puffy).(high, fluffy/puffy).

Warmer

Colder

WarmCold

FrontsFronts

Warm Fronts:Warm Fronts: In a In a warm frontwarm front, warm air, warm air advancesadvances and displaces cold air. and displaces cold air. Since cold air is more Since cold air is more dense,dense, it stays on the it stays on the bottombottom and the and the

warm air rides over the top of it and warm air rides over the top of it and condensescondenses into water into water vapor.vapor.

Weather associated with a warm front is usually a lot of Weather associated with a warm front is usually a lot of cloudsclouds and and rain.rain.

The symbol on a weather map is a The symbol on a weather map is a redred line with red line with red semicirclessemicircles pointing in the direction the warm air advances. pointing in the direction the warm air advances.

Before the front, you would see cirrus clouds (thin and Before the front, you would see cirrus clouds (thin and wispy).wispy).

As the front passes through, you see stratus clouds (low As the front passes through, you see stratus clouds (low gray blanket covering the sky).gray blanket covering the sky).

Cirrus Clouds

Stratus Clouds

Colder

Warmer

Cold and warm front animationCold and warm front animation

FrontsFronts

Stationary Front:Stationary Front: Sometimes, when two air masses meet, Sometimes, when two air masses meet, neitherneither one one

advances.advances. They both stay They both stay stationarystationary.. It’s kind of like a It’s kind of like a battlebattle between the two air masses!between the two air masses! You will probably get You will probably get rain or snowrain or snow and and cloudsclouds with this type with this type

of front, but not always.of front, but not always. Symbol on a weather map is a cold front symbol on Symbol on a weather map is a cold front symbol on one one

sideside and a warm front symbol on the other side. and a warm front symbol on the other side. Since they’re in a “battle” with each other, this can prolong Since they’re in a “battle” with each other, this can prolong

bad weather and make it rain or snow for days.bad weather and make it rain or snow for days.

Warmer

Colder

FrontsFronts

Occluded Front:Occluded Front: Some cold air masses move so Some cold air masses move so fastfast that that

they overtake a warm front.they overtake a warm front. Warm air will get Warm air will get wedgedwedged upward. upward. There are now There are now 22 cold air masses. The cold air masses. The

original one associated with the warm front original one associated with the warm front and the new one that and the new one that overtookovertook the warm the warm front.front.

FrontsFronts

Since warm air is Since warm air is squeezedsqueezed upward, clouds and upward, clouds and rain is very common on both sides of the occluded rain is very common on both sides of the occluded front.front.

Occluded fronts are associated with Occluded fronts are associated with low pressurelow pressure systems.systems.

Symbol is Symbol is alternatingalternating triangles and semicircles. triangles and semicircles. It almost looks like a It almost looks like a zipperzipper. The cold front symbol . The cold front symbol

moves in on the warm front symbol and zips moves in on the warm front symbol and zips together to create an together to create an occluded frontoccluded front..

You would expect a mixture of cold front clouds You would expect a mixture of cold front clouds and warm front clouds with an occluded front.and warm front clouds with an occluded front.

Occluded front animation

FrontsFronts

ESRT ALERT!!ESRT ALERT!! – – bottom of page bottom of page 1313 gives you the front gives you the front symbols with their symbols with their names for free!!names for free!!

Putting it All TogetherPutting it All Together

Using all of this information, weather Using all of this information, weather forecastingforecasting can be done by meteorologists. can be done by meteorologists.

In addition, In addition, weather mapsweather maps can be created on can be created on a daily basis, or even on an hourly basis, a daily basis, or even on an hourly basis, using this information.using this information.

Weather ForecastingWeather Forecasting

Weather MapsWeather Maps

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