Planet Earth - Air Pressure and Wind Unit (Mr. Brown)

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H (blue)

H (blue)

High Pressure

L (red)

Low Pressure

Green and Purple on a weather map

Precipitation

Airmass

A large body of air defined by its temperature and humidity characteristics and bordered by fronts

Determined by the location of forming

The temp and humidity of an airmass

Arctic Class

From high latitudes (66-90 degrees) - Very cold (A)

Polar Class

From mid latitudes (33-65 degrees) - Cold (P)

Tropical Class

From low latitudes (0-32 degrees) - Warm (T)

Maritime Class

Originates over ocean - Humid (m)

Continental Class

Originates over land - Dry (C)

Fronts

Boundary between two air masses of different temperatures or humidity that meet up (named by the air mass moving into the region)

Fronts on a map are noticeable by

Sharp temperature changes over short distances, changes in humidity, rapid shifts in wind directions, pressure changes, clouds/precipitation patterns (more clouds and precipitation on fronts)

Warm Front

Noted by cold air retreating from an area (Red half circles pointing in the direction of movement)

Cold Front

Noted by cold air advancing and wedging up warmer air (Blue triangles pointing in the direction of movement)

Occluded Front

When a cold front catches a warm front and merges lifting the warm air off the surface altogether (Purple alternating triangles and half circles pointing in the direction of movement)

Stationary Front

When two different air masses meet but neither is powerful enough to move or displace the other (Red half circles and blue triangles alternating in opposite directions)

Arctic Polar Vortex

Strong band of westerly winds forming in the stratosphere between 10 and 30 miles above the north pole - encloses lots of cold air and when unstable spills into the continents causing cold spells/long term winter weather)

Polar Jet Stream

5-9 miles above earth's surface separating cold northern air from warm southern air (influences day to day winter weather)

Sudden Stratosphereic Warrings

Spike in polar stratospheric temps (when the polar jet stream becomes wavy and lets cold air down)

Polar Vortex is Influenced by

"large scale atmospheric waves" - sea ice or surface temp changes (can increase major winter events)

Have they discovered the long term trend of the Polar Vortex?

No, sea ice can either destroy or help the polar vortex

Wind

Movement of air from high to low pressure as air tries to equalize pressure

Pressure Gradient

The change in pressure over a distance (closer lines on a map means steeper gradient/more wind - lines called isobars)

What Causes Wind to Blow (speed/direction)

Pressure gradient - wind speed (due to unequal heating usually)/Friction - both (low friction over a lake high friction in a forest)/Coriolis effect - direction (Rotation of the earth curving wind - Northern hemisphere wind curves right Southern it curves left)

Local and Region winds

Caused by temperatures and pressure (high to low)

Local Winds

Sea breeze - Land warms more than water and the hot air on land rises so cold air comes in to fill the pressure gap and the warm air goes over the sea and cools etc.

Regional Winds

Monsoons - a wind system that changes direction seasonally

Cyclones (low pressure) and Anti-Cyclones (high pressure)

Large rotational weather patterns caused by the coriolis effect

High Pressure

Anti-Cyclone, sunny, wind spirals down and out (clouds disapear as air decends), clockwise rotation

Low Pressure

Cyclone, cloudy/stormy, wind spirals up and in, counterclockwise motion

Low Pressure Slogan

When the pressure is low prepare for clouds, rain, or snow!

Cyclone Sizes

Largest - Mid-latitude cyclone (east coast AKA nor easter & bomb cyclone)/Middle - Hurricanes (state size)/Small - Tornado (miles)

Hurricane

Needs warm air and large still oceans over 26.5 degrees C - low altitude winds (June 1st to November 30th = hurricane season) - Can get 12-15 km wide - spinning caused by Coriolis effect (creates eye of hurricane) - sometimes winds 200 km/h

Cyclone Location

Southern Hemisphere - South Pacific, Indian, and south Atlantic oceans

Hurricane Location

North Atlantic (east coast) - Northern Pacific ocean

Typhoon

North Western Pacific ocean

Anti-Cyclone

A high pressure system characterized by outward flow of air (when the pressure is high expect clear sky) - Northern hemisphere the air spirals out and down

The Great Red Spot

An anti-cyclone on Jupiter where the clouds are under another layer of atmosphere and we can see 200-300 miles deep into Jupiter

Jet Stream

River of air in the troposphere - boundary of polar/tropical air masses - flows from east to west - when it bends it helps cyclones and anti-cyclones travel

Look at the weather station model:

https://docs.google.com/document/d/1BQlPH0ticnXroHNMAoXO0nA1KmVzWrRVP4zd8W73PYg/edit

Warm Front Weather

Cirrus -> Stratus -> Nimbostratus -> Overcast Skies and moderate drizzle

Cold Front Weather

Cumulonimbus clouds along warm air wedging area - thunderstorms/heavy precipitation (can cause hail and tornados)

Occluded Front Weather

Complex weather - heavy rain/blizzards in warm and cold seasons

Stationary Front Weather

Stagnant wind and temperatures - altocumulus clouds and light to moderate precipitation

Major Deserts on Earth

On 30 degrees north and south latitudes

Pressure Belts and Wind Currents

See image