Living in Our Ocean of AirChapter 1-2 WX Elements

• Source: http://www.geog.ucsb.edu/~joel/g110_w06/lecture_notes/sun_angle/agburt02_12.jpg

• Angle of incoming radiation and hours of sunlight affect heating.

• Source: http://easyweb.easynet.co.uk/~geography.net/kew/factors(1).htm

• Wind will flow from high to low.

• Hot air rises generating an area of low pressure.• Air cools as it rises and falls generating an area of

high pressure.

• In the northern hemisphere, low pressure rotates in a counterclockwise direction.

• In the northern hemisphere, high pressure rotates in a clockwise direction.

• Source: http://myweb.cwpost.liu.edu/vdivener/notes/High-Low%20map.gif

Wind FactsAir moves horizontally from an area of high pressure to an area of low pressure.

Wind FactsWind speed is measured with an anemometer.

Wind Facts

• is cooling caused by the wind.

• Local winds blow over a short distance.

Wind Facts• sea breeze- air over the water is cooler and

denser than air over land. The flow is from higher pressure to lower pressure.

Wind Facts• land breeze - at night air over land is

cooler and denser. Air flows from higher pressure to lower pressure.

Wind Facts

• Global winds blow steadily from specific directions over long distances.

Why did Columbus landIn the Caribbean Islands? Wind Graphic Display

Wind Facts

• The Coriolis Effect, curvature of the wind, is caused by Earth’s rotation.

Gaspard Gustave de Coriolis

Wind Facts

• Jet streams are high-speed winds about 10 km above Earth’s surface.

What’s happening right now? What does it mean for weather for the next little while?

Dust Storm

Links

• GOES satellite image index• Weatherunderground.com

Types of Clouds

TYPE Cumulus(pile up)

Stratus(layered)

Cirrus(wispy)

LOWAlt:MIDDLEAlt:

HIGHAlt:

Low Clouds

• Stratus• Sheet - like cloud.• No turbulence.• May be risen fog.• Light drizzle or snow.• Close to Earth’s surface.• Can hide danger.

Low Clouds• Stratocumulus

• Rolls or global masses.

• Bulbous protrusions.• Heavy rain and snow• Varying turbulence.• Masks higher severe

cloud buildups.

Low Clouds

• Cumulonimbus• Vertical growth

group.• Top has anvil shape.• High winds, snow,

hail, rain, lightning, and tornadoes.

• Extreme turbulence.

Low Clouds

• Nimbostratus• Shapeless, low-level,

moderate precipitation.• Fog and precipitation

found beneath.• Visibility restricted.• Calm to light winds.

Middle Clouds

• Altostratus• Relatively thin.• Sun may be seen

through veil.• Ice crystals and

super-cooled water.• Light precipitation.• Poor surface

visibility.

Middle Clouds

• Altocumulus• Wavy solid clouds

with rounded outline.• Light intermittent rain

or snow.• Commonly followed

by thunderstorms.• Poor visibility and

moderate surface winds.

High Clouds

• Cirrus• Thin feathery

clouds.• No precipitation.• Sign of

approaching bad weather.

High Clouds

• Cirrostratus• Thin, resembles a

sheet or veil.• No precipitation.• Nearly transparent.• Often sign of

approaching bad weather.

High Clouds

• Cirrocumulus• Thin clouds.• Indicates high-level

instability.• Similar to cirrostratus

but they have a slightly “bumpy” appearance.

Fracto and Lenticular

• Fracto• Broken and/or

ragged.• Cumulus fractos.

• Lenticular• Lens-like shape.• Tells turbulence,

visibility, precipitation.

–

Cumulus with Vertical Growth

• Fair weather cumulus• A puffy, cottonball

appearance.• Develops from

thermal updrafts.• Flights below can be

bumpy and choppy.

Cumulus with Vertical Growth

• Vertical growth, or building cumulus• Produce strong rain

and moderate to severe turbulence.

• Very strong updrafts. • With further building

and increase in intensity, it becomes a thunderstorm.

Fog Types

• Radiation Fog

• Formed at night when land surfaces radiate much of the heat absorbed from the Sun back into space.

• The cool land surface cools the air near it to below the dew point and fog is formed.

• High Inversion Fog

• A low fog.

• Formed by condensation of water vapor at or near the top of cool air, which is overlain by a warmer air layer.

Fog Types

Air Mass Type and Origination

Air Mass Type and Origination

• Air masses are identified by letter symbols.• A polar air mass (P) is cold.• A tropical air mass (T) is hot.• A maritime air mass (m) forms over water

and is humid.• A continental air mass (c) forms over land

and is dry.

Air Mass Type and Origination

• Aviators and meteorologists in the continental United States are chiefly concerned with air masses origination at two sources.

• Masses that move southward from Polar Regions.

• Masses that move northward from Tropical Regions.

Air Mass Type and Origination• Cold air masses

• Continental polar (cP)• Maritime polar (mP)• Arctic (A)

• The principle warm air mass is maritime tropic (mT)

Temperature Classification of Air Masses

• Based upon its temperature in relation to the surface over which it passes.

• A cold air mass (k) is cooler than the Earth’s surface over which it is moving.

• A warm air mass (w) is warmer than the Earth’s surface over which it is moving.

Temperature Classification of Air Masses

• Continental polar cold (cPk) - originates in the polar zone and moves south over a warm surface.

• Maritime tropical warm (mTw) - originates over the Gulf of Mexico and moves toward the north over a cold surface.

Characteristics of Air Masses• As an air mass moves away from its source,

its original characteristics are changed because of the surface it passes over. It may:• Become warmer or colder.• Absorb or lose moisture.• Be lifted up by mountains or subside into

valleys.• Cold air masses move more rapidly than

warm air masses.

Fronts

• The boundaries between air masses are called frontal zones or fronts.

• This boundary or front moves along the Earth’s surface as one air mass displaces another.• If a cold air mass replaces a warmer air mass,

the boundary is called a cold front.• If a warm air mass replaces a cold air mass, the

boundary is called a warm front.

Cold Front

Fronts

• Cold Fronts• As warm air is forced upward, it cools,

condenses into clouds, creating thunderstorms.• If movement is rapid, with an abundance of

water vapor, violent weather takes place.• Squall lines develop ahead of the front.

Fronts

• Cold Fronts• Along the cold front there will be a low-

pressure cell where the weather is at its worst.• Almost any type of clouds can be found near the

cell.• Poor visibility, low ceilings and rain in summer.• Freezing rain and snow in winter.

Warm Front

Fronts

• Warm Fronts• Connected to a low-pressure cell, travels

northeastward.• If cell did not move, the front would dissipate.• Front slips upward over cool air and forms a

wedge.• Rises slowly which delays condensation.

Fronts

• Warm Fronts• Front is announced by cirrus clouds.• As front approaches other clouds, skies darken.• Near the frontal boundary, clouds are low,

gentle rain falls and visibility is poor.• Warm rain falling into cooler air causes fog.

Fronts

• Warm Fronts• After front passes, there is a rise in temperatures,

general clearing and change in wind direction.• In winter a warm front causes icing conditions at

low altitudes.• In northern latitudes snow may also be

produced.

Stationary Front

Fronts

• Stationary Front• When air masses stop, a stationary front

develops.• Weather can be bad for aviation along the front.• About every form of weather can be found.

Front

• Stationary Front• Toward the trailing edge of the any front there

will be a stationary-front condition.• The trailing edge stationary fronts are a great

distance from the parent cell.• As the distance become greater the front no

longer exists.

Occluded Front

Front

• Occluded Front• There is a tendency for a horizontal bend or

wave to occur along the front.• After a frontal bend starts, cold air moves ahead

of a warm front.• The cold section moves faster than the warm

section.

Terrain Factors

• The presence of mountain ranges change the characteristics of a front.

• As air masses enter the United States the mountains cause them to rise.

• Along many seacoasts there is a breeze from the sea by day. This moist, relatively cool air rises and heats as it passes across land.

• Convectional clouds form and bring afternoon showers.

Terrain Factors

• At night the land cools and the breeze blows toward the sea.

• Wind blowing toward land formations and condensation will occur.

• The reverse can happen if the wind forces clouds downward into warmer air.

Turbulence

• Thermal Turbulence• Intense surface heating causes convection

currents.• More intense convection currents occur over

dark-colored ground.• Less convection currents will be over light-

colored ground.• Because velocity varies turbulent conditions are

expected.

Turbulence

• Thermal Turbulence• Presents the biggest problem for aviators during

landing.• To eliminate during normal flight, climb above

clouds.• Not confined to summer months.• When cumulus clouds are present, convection

currents and thermal turbulence exists.

Turbulence

• Mechanical Turbulence - Low Level• Results from strong wind gusts over rough

terrain or manmade features.• Produces turbulent eddies below 500 feet.

Turbulence

• Mechanical Turbulence - Mountain Wave • Caused by wind speeds of 25 knots or stronger.• Produces a large-scale wave motion.• Extends from ground level to tropopause and

300 nmi downwind.• Most intense turbulence will occur within the

first two or three waves.

Turbulence - Wind Shear

VIDEO OF WIND SHEAR

Turbulence• Wind Shear -

Low Level Wind Shear (LLWS)• Occurs below

10,000 feet.• Primarily caused

by frontal systems, low level jet streams and thunderstorms.

• Occurs rapidly.http://www.pbs.org/wgbh/nova/balloon/science/jetstream.html