Meteorology 1050 Mizzou Exam 3, ATSM Exam 3

Warm Front

Red rounded pips

Light rain

Cold Front

Blue Triangles

Usually active front

Stationary Front

Alternating colors, no movement

Least active

Most different between masses

Occluded Front

Purple pips and triangles, fronts collided

Strong low pressure

Dryline Front

Yellow tight pips

Separates moist and dry air

Continental Polar (cP) air mass

Cold and drier air, brings down from the north

From ice and snow covered regions of Alaska and Canada

Continental Arctic (cA) air mass

Colder and drier air, brings from the north

From ice and snow covered regions of Alaska and Canada

Continental Tropical (cT) air mass

Hot and dry, Mexico deserts

Maritime Polar (mT) air mass

Forms over cold water, causes winter storms

North Atlantic, North Pacific

Maritime Tropical (mT) air mass

Warm moist air, California, "Pine express"

Sub-tropical Pacific, the Gulf of Mexico, and/or the South Atlantic moves inland

Pineapple Express

It is a Maritime Tropics air mass that brings rain and mudslides to California in the winter

What is the Jet Stream?

Jet streams are fast flowing, narrow air currents found in the atmosphere around 36,000 ft

Difference between temp. and moisture properties on either side of the Jet Stream?

It separates cold air above it from warm air below it. Also separates nice weather from unsettled weather

Polar Jet Stream

Northern Arctic air, affects in winter

Subtropical Jet Stream

Southern warm moist air in the summer

Low-Level Jet (LLJ)

Forms over the great plains / close to surface, 100 meters, half the speed and advects moisture. Strongest at night and weakest in midmorning.

High Pressure Systems

Warm air at the surface, clockwise, lower winds, unsettled weather

Low Pressure Systems

Cold air at the surface, counter clockwise, faster winds, fair and calm weather

If you are located to the WEST of a HIGH-PRESSURE SYSTEM, you would expect the wind to be:

Southerly

*Why?

Winds blow out and away from high pressure and in towards the center for low pressure.

Inward flowing = converge

Outward flowing = diverge

LOOK THIS OVER

What is the "General Circulation of the Atmosphere?"

Long term average wind over the globe

Where are the Mid-Latitudes and why is the weather so "changeable?"

Mid-latitude is where we live and it is so changeable because we are next to the equator

Single Cell Model

HOT air moves from the equator toward the poles and COLD air moves from the poles toward the equator. It's not possible due to Coriolis

Hadley Cell

Surface winds from the north to south and are turned right by Coriolis

Ferrell Cell

Surface winds move south to north and turn right

Polar Cell

Surface winds move north to south and turn right

Intertropical Convergence Zone (ITCZ)

Area of lower pressure with convergence of air and rising motion. Lots of thunderstorms and rain. ALWAYS found along the equator. Result of trade winds converging in one location.

El Niño

Refers to a warm ocean current appearing annually around Christmas time in the Pacific Ocean.

Typically, it lasts only a few weeks to a month or more.

Every two to seven years, an El Niño event may last for many months, having significant economic and atmospheric consequences worldwide

Chinook Winds

Warm dry wind that descends the eastern slope of the Rocky Mountains, strong westerly winds aloft flow over a north/south oriented mountain range

Katabatic Winds

Downslope winds flowing from high elevations of mountains, plateaus, and hills down their slopes to the valleys or planes below

Santa Anna Winds

A warm and dry down slope wind in California that enhances wildfire risk. A persistent (blocking) high over the rockies produces strong winds over the Santa Anna region of California

Dry wind that creates a very dry atmosphere.

This is prime for development of forest fires

Land and Sea Breezes

Breeze coming from the land is land breeze and sea a sea breeze.

Mountain and Valley Breezes

Valley breezes occurs when the warm air rises up the sides, warm air in a mountain breeze will rise up the middle.

During the night the slopes get cooled and the dense air descends into the valley as the mountain wind.

Dust Devils

Spinning vortices commonly seen on hot days in dry areas (deserts)

Monsoons

A seasonally driven change in wind direction.

Large scale high-pressures over land cause winds to blow from the land toward water areas. Divergence of air over land causes outward motion and dry weather is enhanced.

Wet vs. Dry Monsoons

Wet- Large scale heating in the summertime over land causes winds to blow from the water areas toward land, convergence causes upward motion and rainfall is enhanced.

Dry- Large scale high-pressure over land causes winds to blow from the land toward water areas. Divergence of air over land causes outward motion and dry weather is enhanced.

Wind from Degrees to Cardinal Directions

45 Degrees is Northeast

Wind Vane

Spins on a post and points wind direction

Aeorvane

Points into wind and has propellers for wind speed

Anemometer

Cups a pole and spins with the wind

Wind profiler

A vertical pointing radar that can tell how much wind changes with height

Pilot balloon

Weather balloon

Radiosonde

The instrument package on a pilot balloon designed to measure

TEMP, HUMIDITY, PRESSURE, WIND

Planetary scale

Largest scale, includes longwave in the westerlies 10,000 km or larger, weeks or longer

Synoptic Scale

Large scale, includes high and low-pressure system, 500 - 200 km, days to weeks

Mesoscale

Middle scale, includes fronts and thunderstorms, few km to 500km, hours to days

Microscale

Smallest scale, includes tornados and smaller winds, less than 1 km, minutes to an hour

What is the PBL?

Planetary Boundary Layer- AKA atmospheric boundary layer or friction, lowest 3000 km, surface friction is important

Pressure Gradient Force (PGF)

The horizontal difference in pressure

Coriolis force

An apparent force created by the rotation of the earth.

Deflects objects from a straight path

Wind deflects to the right in the N Hemisphere

Coriolis Force varies with: Rotation of the earth, latitude, speed of object, newtons laws of motion

Air will flow from high pressure to areas of low pressure. Why?

It's like a vacuum.

On an upper-level chart, normally we find warm air associated with ____ pressure, and cold air associated with ____ pressure.

High/Low

​Which of the following is MOST likely associated with fair weather?

high pressure area

A ridge on an upper-level isobaric chart indicates

higher-than-average heights.

Meridional wind-flow patterns go

from either north-to-south or south-to-north.

We can generally expect the air to be ____ above areas of surface low pressure and ____ above areas of surface high pressure.

Rising/Sinking

​The pressure gradient force is non-existent at the equator.

False

Which of the following instruments measures air pressure?

Barometer

Choose ALL of the following activities that must be concerned with the effect of Coriolis force.

A Southwest Airlines flight from Seattle, Washington to New York, New York., An ICBM (Intercontinental Ballistic Missile)Flight,

Atmospheric air pressure always _____ with height.

decreases

Suppose a parcel of air has a given temperature, pressure, and density. If the parcel's size remains the same while its temperature increases, then the air pressure inside the parcel will

increase

T/F Strong winds blowing over vegetation results in rapid water loss in the plant.

True

​The howling of wind on a blustery night is believed to be caused by

air flowing past obstructions.

T/F Wind direction and speed can be determined with an aerovane.

True

Most people associate a monsoon with heavy rain and wind. While that is true (somewhat), the term monsoon actually refers to what?The United States has a monsoon season. Where is it located?

A wind system that changes direction, seasonally. The desert southwest.

​On the eastern side of the Rocky Mountains, chinook winds are driest when

​clouds form and precipitation falls on the upwind side of the mountains.

​Wind gusts are caused by

turbulent eddies.

T/F

True

When wind encounters a solid object, a whirl of air, called a(n) ____________________, forms on the object's leeward side.

Eddy

​An offshore wind blows

​from land to water.

​Surface winds are generally strongest and most gusty

in the afternoon

The subtropical jet stream is usually found between​

​20° to 30° latitude, 200-mb level.

​​Pilots prefer to fly in the core of a jet stream (especially when flying west to east). (T/F)

True

Most of the United States is located within the prevailing ________ wind belt.

westerlies

Upwelling is

the rising of cold water from below.

Jet streams sometimes split into two branches (T/F)

True

In the Northern Hemisphere, air found to the north of the polar front is ____, while air further south is ____.

​cold; warm

​The position of the Pacific high over the North Pacific Ocean shifts ____ in winter and ____ in summer.

southward; northward

The name given to the current of warm water that replaces cold surface water along the coast of Peru and Ecuador during December is

​El Niño.

You are given an upper-level map that shows the position of two jet streams. You would be able to tell which is which, because the subtropical jet stream forms to the ____________________ of the polar-front jet.

South

Why is the polar jetstream strongest in the winter and weakest in the summer (in the northern hemisphere)?

The general circulation of the atmosphere shifts south toward the equator, drawing in colder air from the arctic into the United States.

Occluded fronts are colored _____ on a surface weather map.​

Purple

What type of air mass would be responsible for refreshing cool, dry breezes after a long summer hot spell in the Central Plains?

​cP

A true cold front on a weather map is always

​followed by cooler air.

In the Central Plains of the United States, continental polar air is common in both winter and summer.

False

During the spring, on a warm, sunny day in Boston, Massachusetts, the wind shifts from southwesterly to northeasterly and the weather turns cold, damp, and overcast. This suggests that a "back door" cold front approached Boston from the

​northeast

An air mass is characterized by similar properties of ____ and ____ in any horizontal direction.

​temperature; moisture

Record breaking low temperatures are associated with which air mass?

​cP

​On weather maps cold fronts are drawn

​in blue, with arrowheads showing the front's general direction of movement.

Cold fronts are colored purple on a weather map. (T/F)

False

The lake effect occurs when a(n) ____ air mass moves over a ____ body of water.

cP; warm