ATMO EXM 3 DICKEY

Global Circulation

basic cause of general circulation is UNEQUAL HEATING of earth’s surface

3 cell Model

Model identifies 3 distinct cells in each hemisphere: Hadley, Ferrell, and Polar

Hadley Cell

thermally direct convection cell near EQUATOR, where hot air rises at ITCZ and sinks at roughly 30 degrees latitude or Subtropical Highs

ITCZ

Intertropical Convergence Zone, where hot air rises for Hadley Cell

Ferell Cell

located in mid-latitudes (30-60 degrees), where air moves toward the poles at the surface

Polar Cell

located at poles, cold air sinks at HIGH and moves towards the EQUATOR as polar Easterlies

NE/SE Trade Winds

Flow from the subtropical Highs toward the Equatorial Low ITCZ

Westerlies

surface winds in the mid-latitudes that turn to the right due to FERELL CELLS

Polar Easterlies

cold surface winds flowing away from the poles

Jet Streams

fast moving bands of water, 2 types

Polar Jet

upper-level boundary, between Polar and Ferrell cells, dividing line between warm and cold air

Subtropical Jet

boundary between Hadley and Ferrell cells, AFFECTS TX WEATHER in winter

Sea-Breeze

OCEAN TO LAND, coastal breeze, edge: leading edge sea-breeze front, daytime

Land Breeze

Land-Sea breeze HAPPENS AT NIGHT

Valley Breeze

diurnal wind patterns where air flows UP mountainsides, DAYTIME

Mountain Breeze

air flows DOWN and at NIGHT

Santa Ana Winds

hot dry winds blow from desert toward coast in Southern Cali

Haboob

massive dust storm triggered by thunderstorm downdraft

ENSO

EL Nino Southern Oscillation, synoptic scale event impacting global weather

Upwelling

movement of cold nutrient rich water from deep ocean to surface, along Peruvian coast

Walker Circulation

East to West thermal circulation that weakens or reverses EL Nino

Impact On Texas

El Nino causes cooler and wetter condition during Winter in TX

Air Mass

a large body of air with similar temp and humidity characteristics

Air Mass Source Regions

areas with light wind EX: Oceans, Deserts, Arctic. Great Plains NOT a good region

Continental Arctic

extremely cold and dry

Continental Polar

cold and dry typical behind a cold front

Maritime Tropical

warm and moist, fuel for Gulf thunderstorms

Continental Tropical

HOT and dry, appears only in summer in SW united states

Synoptic Scale Features

air masses and fronts

Cold Front

blue line with triangles, leads to sudden temp drop and severe weather

Warm Front

red line with semi circles, leads to warmth and steady precip

Occluded Front

purple line with both triangle and semi-circle, when cold overtakes warm front

Dryline

boundary separating hot, dry air CT and warm moist air MT. common in southern plains and frequent trigger for severe storms

Mid-latitude Cyclones

dynamic low pressure system often forms with fronts

How do mid-latitude cyclones look on satelite?

Like commas , have a hook

Cyclogenesis

development or strengthening of a mid-latitude cyclone

Upper-level Support

for surface low to strengthen there must be upper-level divergence that is greater than surface convergence

Ingredients for a Thunderstorm

Moisture, Instability, and Lift

Severe Criteria for thunderstorms

Hail less than 1 inch, Wind gusts greater than 50kt or 58 mph, or a tornado

Ordinary Cell

lasts 1 hr, dies when downdraft cuts off updraft

Supercell

many hours, since updraft rotates, keep precip/downdrafts separate from inflow

Updraft Characteristics

rising warm, moist air

Downdraft characteristics

formed by rainfall evaporating, makes air heavier and colder

Squall lines

long line of convection forms ahead of a cold front

Doppler Radar

critical because shows motion and rotation within a storm

Charge is ___ at top (anvil) and ground (trees)

positive

charge is _____ at bottom/middle cloud.

negative

What is charge separation?

when warm hail transfers positive ions to colder ice crystals.

Heavier negatively charged hail ____.

sinks

Positively charged ice crystals are at the ___.

top

What is a stepped leader?

initial ionized pathway that leads the way downward before visible lightning strike

Types of Lightning

Forked (classic lightning), Heat (the distance one), Ribbon (smooth transfer)

Why are global westerlies located only in the mid-latitudes?

Ferrell cells produce southerly winds at the surface which turn to the right

What do we call the semi-permanent high in the Atlantic Ocean

Bermuda High

Which band is fast moving wind is located at the upper-level boundary between Hadley and Ferell Cells

Subtropical Jet

Upwelling in the ocean makes surface water temperatures

Colder

The thermal circulation that reverses or weakens during El Nino, what was it called?

Walker

Why is the Great Plains NOT a source of region?

Too Windy

It hasn’t been this cold in CSTAT since 1899. This statement most likely to be uttered when experiencing which air mass?

Continental Arctic

Air masses and fronts fit which scale?

Synoptic Scale

What color and shape tells you it’s a warm front?

Red and semi-circle

Which front is moving faster as occlusion develops?

Cold

I am driving towards the South and approaching a warm front. If the system supports mixed precip, I might expect?

Snow, Sleet, Freezing Rain, then Rain

What might cause air masses to move?

Uneven heating of earth’s surface

Ice storms are more likely to form with?

A warm front, because cold freezing air is trapped at surface

A dryline indicates the boundary between air masses with different?

humidity

Which letter indicated the triple point?

B, where red semicircle, blue triangles and purple meet

Which letter indicates a warm sector?

B, because warm moist air located between advancing cold front

What do we call when a Low Forms with fronts?

mid-latitude cyclone

On this 500mb chart where is divergence

D.) Orange downwind produces a U

The winds aloft that would form or strengthen a surface low would be

Diverging

For an upper level low to strengthen a surface low, the upper level low needs to be?

west of the surface low

The level at which a raised parcel becomes less dense than the surrounding environment?

Level of Free Convection

Ordinary thunderstorms only last about 1 hour and begin to dissipate when?

the downdraft spreads throughout the cloud and cuts off the updraft

What creates the downdraft in a thunderstorm?

rainfall evaporating making the air heavy

For a thunderstorm to be more than ordinary the most vital atmospheric ingredient is?

Shear

When the downdraft from a thunderstorm reaches the ground, we call the outflow boundary of the cold air

Gust front

The main thing that makes a supercell different from other severe thunderstorms is

Rotation

Charges become separated into positive and negative in a thunderstorm because

Positive ions move from warmer ice to colder ice

You see a thunderstorm with a swirl of blowing dust rising underneath it. NOT ROTATING HORIZONTALLY. what is causing this

dust devil