Exam 2 part 3

Ridge

A ridge is an elongated region of relatively high atmospheric pressure, the opposite of a trough.

Trough

A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.

T/F air moves from low pressure to high pressure

False from high pressure to low pressure

What type of pressure is associated with divergence at the surface

High

Prevailing Wind

Prevailing winds are winds that blow predominantly from a single general direction over a particular point on the Earth's surface.

Siberian High

High pressure system over asia

Explain why air pressure decreases with increases in altitude in the troposphere?

because the higher you go less air is pressing down on you therefore less pressure.

Low

causes wet weather winds converge towards low pressure

Anticyclone

comes from a high pressure system air around is relatively low air comes down on high pressure and diverges, air spins to the right in Northern hemisphere left in the southern hemisphere

If air is diverging at the surface what is it doing aloft?

converging

What atmospheric processes cause land and sea breeze?

daily temperature contrasts between land and sea and the pressure patterns generates a sea breeze, land heated more intensely than water air above land heats and creates low pressure

Does pressure increase or decrease with altitude?

decreases

Geostrophic Winds

due to the pressure gradient and Coriolis force being in equilibrium.

Sea Breeze

during day, land heated quicker than water, air above land heats creating low pressure. warm air rises from shore forms clouds goes over over colder air sinks then spreads along surface of water and blows to shore

Valley Breeze

during the day air along mountain slopes is heated more intensely than the air in the bottom of a valley this leads to warm air rising up along the mountain slope and creates a valley breeze.

Land Breeze

ground cools at night cool air above it creates high pressure flows out over warm ocean air rises over ocean and flows back to land

A gradual pressure gradient is associated with what type of pressure system?

high

An anticyclone is associated with what type of pressure system?

high

What type of weather is associated with high pressure and low pressure?

high pressure lighter winds sunny low pressure stronger winds wet

Cold air = ______ pressure Warm air= _______ pressure

higher / lower

What is the name for lines that connect areas of equal pressure?

isobars

Briefly describe how the Coriolis force modifies the movement of air.

it makes it curve right in the northern hemisphere and left in the southern hemisphere

What is the thermal equator?

latitude where noontime sun is directly over head

In the southern hemisphere Coriolis force causes deflection to the ______.

left

A cyclone is associated with what type of pressure system?

low

What is the difference between low pressure and high pressure

low pressure is formed when air rises while high pressure is formed while air sinks

Cold,dense air is sinking at the polar high and moving towards _________.

lower latitudes

Pressure Gradient

measures the differences in pressure over time

Convergence

moves towards center

Divergence

moving away from center

What is the jet stream?

narrow ribbon of high-speed winds that meander for thousands of kilometers, 10 to 12 km in altitude 100+ kt wind speed

Hadley Cell

once cell model, was aware that solar energy drives winds, he proposed that the large temperature difference between the poles and the equator creates once large consecutive cell in each hemisphere

Be able to draw each of the global circulation models and name each cell.

page 124

Be able to locate the following global pressure belts A. Equatorial Low B. Subtropical High C. Subpolar Low D. Polar High

page 125 or file on computer

What are the horse latitudes? What is the story between the horse latitudes?

place where there is very little wind; sailors used to throw horses over board at these places; in the subtropical high

Wind speed and direction are controlled by what three factors?

pressure gradient force, Coriolis force, friction

Winds form the jet stream typically blow from ______ to _______.

west / east

Santa Ana

warm dry air that moves down the side of a mountain (chinook) these hot dry dust beating winds invade california during autumn and bring warm temps.

What are chinook winds and Foehn winds?

warm dry winds sometimes move down east slop of the Rockies called chinooks, the alps have similar wind patterns these are called the Foehn

Where do Santa Ana winds originate and why do they move into southern California Region?

1. high pressure in the great basin area of Idaho and Utah pushes toward low pressure off the southern California coast 2. The high-elevation Sierra Nevada Mountains block the winds and force them to the north and south 3. The desert helps heat and dry the wind as it moves south 4. As the winds move from higher to lower elevations and squeeze through narrow canyons they are heather further and pushed to higher speeds. 5. The heated dry air is forced through passes and canyons including Santa Ana canon from which the wind's name derives towards the coast.

What is the standard Sea level pressure?

1013.25 mb

What is the standard sea-level pressure in millibars? In inches of Mercury? In pounds per square inch?

1013.25 mb 1013.25 hpa, 29.92 hg

Is precipitation greater than or less than evaporation at the following locations A. ITCZ B. Subtropical High C. Subpolar Low

A. Precipitation is greater than evaporation B. Precipitation is less than evaporation C. Perception is greater than evaporation

Define the following scales of weather events and give an example of each: A. Macroscale B. Mesoscale C. Microscale D. Synoptic

A. Weeks at a time (trade winds) B.Several Minutes and may exist for hours (thunderstorms, land and sea breezes) C. from a few seconds to minutes (dust devils, wind gusts)

How long to weather events at the various scales above last? A. Macroscale B. Mesoscale C. Microscale D. Synoptic

A. Weeks at a time (trade winds) B.Several Minutes and may exist for hours (thunderstorms, land and sea breezes) C. from a few seconds to minutes (dust devils, wind gusts) D. Smaller macroscale event (cyclones, anticyclones)

What is the pressure gradient force?

Air moves from high pressure to low pressure differences in pressure over a distance.

How are winds formed?

Air moving from low pressure to high pressure

Explain the formation of a geostrophic wind.

As the air moves from the high pressure area, its speed increases, and so does its Coriolis deflection. The deflection increases until the Coriolis and pressure gradient forces are in geostrophic balance: at this point, the air flow is no longer moving from high to low pressure, but instead moves along an isobar.

Write a generalization relating to spacing of isobars and the speed of winds.

Closer together stronger winds further apart lighter winds

Explain why a cold, dry air mass produces a higher surface pressure than a warm, humid air mass.

Cold air sinks, warm air rises

Polar High

Cold dense air sinks, air diverges toward lower latitudes.

Isobar

Connects area of equal pressure

Compare the convergence and divergence

Convergence winds come together around a low pressure system divergence winds go away from a high pressure

If air is diverging at the surface what is it doing at the surface?

Converging

if air is diverging aloft what is it doing at the surface?

Converging

during what part of the day do sea breezes occur?

Day

If air is converging aloft, what is it doing at the surface?

Diverging

If air is converging at the surface what is it doing aloft?

Diverging

Coriolis force is zero at ______, thus tropical cyclones can not form in this region.

Equator

What is the name of the convergence zone that migrates through the tropical latitudes?

Inter Tropical Convergence Zone

What is the position of the ITCZ in july/ January?

It is further north in july around the equator then moves south in January just below equator

A steep pressure gradient force is associated with what type of pressure system?

Low

What type of pressure is associated with convergence at the surface?

Low

Subpolar Low

Low responsible for much of the stormy weather in the middle latitudes particularly in the winter

What are the three units used to measure atmospheric pressure?

Milibars, hectopascals, inches of mercury

Jet Stream

Narrow ribbons of high-speed winds that meander for thousands of kilometers blow from west to east flow can shift from north to south creates low pressure; on west ward flights these are avoided, and there is a steep pressure/temperature gradient; where warm subtropical and cool polar air Masses meet.

During what part of the day do land breezes occur?

Night

Be able to draw the direction of global prevailing winds.

Page 125 or file on computer

Where is Coriolis force at its maximum?

Poles

The geostrophic winds are caused by the equilibrium of ________ and _________.

Pressure Gradient Force and Coriolis Force

what are the names of the two general circulation models?

Single Cell Model; Three Cell model

What are the causes of the subtropical high?

Sinking air in the subtropics piles up and must diverge. Sinking air causes clear skies and warm temperatures

Subtropical High

Sinking air in the tropics piles up and must diverge, sinking air causes clear skies and warm temperatures

Trade Winds

The trade winds (also called trades) are the prevailing pattern of easterly surface winds found in the tropics, within the lower portion of the Earth's atmosphere, in the lower section of the troposphere near the Earth's equator.[1] The trade winds blow predominantly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere, strengthening during the winter and when the Arctic oscillation is in its warm phase.

T/F the subtropical high is the cause of many major deserts around the world?

True

In general, where do warm ocean currents occur? Where do cold ocean currents occur?

Warm Currents - West side of Basin Cold currents - east side of Basin

Foehn

Warm dry winds move down the east side of the alps

Chinook

Warm dry winds sometimes move down east slope of the rockies

Horse Latitudes

Weak winds, subtropical high located between 20 degrees and 40 degrees in both the northern and southern hemisphere

How are winds named?

Where the originate and the direction the wind is blowing

Intertropical Convergence Zone (ITCZ)

Where trade winds converge, promotes thunderstorms follows thermal equator, same as equatorial low

Millibar

a way of measuring sea level pressure; 1013.25 mb

Polar Front

above the tropic of cancer

Doldrums

also known as the horse latitudes

During what months do Santa Ana winds normally occur?

autumn October-March

In the Northern Hemisphere Coriolis force causes deflection to the ______.

right

What causes Coriolis force?

rotation of earth

Where the jet stream occurs there is a steep _____ and ______ gradient.

steep / temperature

What are the two main factors that effect sea level pressure?

temperature and altitude

The ITCZ is associated with what type of wether?

thunderstorms

What causes the ITCZ?

trade winds converging

Coriolis Force

turning of an objects trajectory due to earths oration, right in the northern hemisphere left in the southern hemisphere

High

wind diverges from high pressure sunny weather