Meteorology 1050 Mizzou 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?

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.

Frontogenesis

To strengthen a front, increase the temperature difference across the front

Frontolysis

To weaken a front, the temperature difference across the front

Weather front

Definition #1: a _________ zone between air of different densities.

Definition #2: a __________ between air masses with different characteristics.

Meridional wind-flow patterns go

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

In an aneroid barometer, a general rule is that the higher the reading, the more likely ____ weather will occur, and the lower the reading, the better the chances are for ____ weather.​

clear; inclement

Wind blows around low-pressure areas, and around high-pressure areas in the Northern Hemisphere.

counter clock-wise; clockwise

Which of the following produces the strongest Coriolis force?​

​fast winds; high latitude

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

False

The Coriolis force deflects winds to the_____in the Northern Hemisphere and to the____in the Southern Hemisphere.​

right; left

The unit of pressure most commonly found on a surface weather map is

​millibars or hectopascals.

What is considered standard sea-level atmospheric pressure in millibars?​

​1013.25 mb

The unit of pressure most commonly found on a surface weather map is​

​millibars or hectopascals.

The altimeter and barograph are two types of aneroid barometers.

true

The wind's speed generally increases with height above Earth's surface because

​friction with Earth's surface slows the air near the ground.

Coastal areas can have strong waves on a clear, non-stormy day.

true

Which of the following conditions favor the development of dust devils?

hot, dry days

Wind direction and speed can be determined with an aerovane.

true

Chinook winds are

warm, dry downslope winds.

What is an example of mesoscale motion?

​winds blowing through a city

A pilot enters the weather service office and wants to know what time of the day she can expect to encounter the least turbulent winds at 760 m (2500 ft) above central Kansas. If you were the weather forecaster, what would you tell her?

in the early morning

Storms rank in size from largest to smallest, as follows: middle-latitude cyclonic storm, hurricane, thunderstorm, tornado.

true

Santa Ana winds warm by ____________________ as they flow down an elevated desert plateau.

compression

The size and shape of a turbulent eddy depends upon

​the size and shape of the obstacle.

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

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.

Flowing northward along the east coast of the United States is a tremendous warm water current called the ____________________.​

Gulf Stream

Jet streams sometimes split into two branches.

true

The low-level jet that forms over the Central Plains of the United States in the summer appears to be responsible for​

nighttime thunderstorms.

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

true

In the middle latitudes of the Northern Hemisphere, surface winds tend to blow counter_____ and_____ around an area of surface low pressure.

counter clockwise; inward

The general circulation of the atmosphere represents the actual air flow around the world and not just an average.

false

The polar front jet stream is stronger in the___ than in the ____.

winter;summer

A thermally direct cell is one that

​is driven by energy from the Sun.

Along a dryline, the ____ may drop markedly.

dew point temperatures

On a weather map, sharp changes in temperature, humidity, and wind direction are marked by

a front

Squall lines most often form ahead of a

cold front

A good air mass source region is generally flat and of uniform composition with light surface winds.

true

Regions where air masses originate are known as ____________________.​

source regions

Which air masses are formed in regions where long, clear nights allow for strong radiational cooling of the surface?

​cP and cA

Barometric pressure usually falls with the approach of a(n) ____front or____front.​

cold; occluded

Before the passage of a cold front the pressure normally ____, and after the passage of a cold front the pressure normally ____.

​drops; rises

Clear sunny days with very cold nights would be associated with what type of air mass?

cP

One would expect a cP air mass to be

cold and dry