Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ATM 205 > EXAM 2 > Flashcards

EXAM 2 Flashcards

1
Q

What does the 850 hPa pressure level tell meteorologists about the atmosphere?

A

Surface Temperature conditions in the atmosphere.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does the 700 hPa pressure level tell meteorologists about the atmosphere?

A

Relative Humidity (RH) which helps indicate cloud coverage.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does the 500 hPa pressure level tell meteorologists about the atmosphere?

A

Vorticity (spin) which indicates the location and intensity of midlatitude low-pressure centers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the 200 and 300 hPa pressure level tell meteorologists about the atmosphere?

A

Wind patterns which indicates the location and strength of jet streams.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does the 1000-500 hpa thickness between two pressure levels tell meteorologist about the atmosphere?

A

Average temperature where a larger thickness indicates warmer air and a smaller thickness indicates colder air.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does Horizontal pressure differences lead to the generation of wind?

A

Horizontal pressure difference leads to the generation of wind because air naturally moves from areas of higher pressure to areas of lower pressure in an attempt to equalize the pressure differences. This movement of air driven by pressure gradients, is what we experience as wind.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What conditions are assumed to remain unchanged when considering changes in pressure in an air column and why?

A

The constant density (p) and constant column volume. This means that any change in pressure must be due to a change in the mass or air within the column.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens to the pressure in an air column if more air parcels are added to the volume, and how can pressure be changed in this context?

A

If more air parcels are added to the volume, the pressure (P) in the column increases due to the greater weight of air above the surface. To change the pressure, you need to change the mass of air within the column, since volume and density are assumed to remain constant.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does temperature changes impact pressure in an atmospheric column?

A
  • An increase in temperature leads to lower density (p). (the column is taller therefore pressure decreases with height)
  • A decrease in temperature leads to higher density (p). (the column is shorter therefore lower pressure)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is horizontal pressure gradient force?

A

The force that pushes air horizontally from high pressure areas to low pressure areas.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does temperature differences lead to horizontal pressure gradient forces?

A

Temperature differences cause variations in air density, with warm air being less dense and rising (creating low pressure), while cold air is denser and sinks (creating high pressure). These variations lead to horizontal pressure gradients—differences in surface pressure across distances. The pressure gradient force (PGF) moves air from areas of high pressure to areas of low pressure, generating wind. Thus, temperature differences drive horizontal pressure gradients, which in turn cause winds and atmospheric motion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why is sea level pressure used for measuring pressure at the surface?

A

It is difficult to compare pressure at different locations if not at the same elevation. Therefore, meteorologists use Sea Level Pressure (SLP) as a common reference level.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do you convert a surface pressure measurement to sea level pressure?

A

Add 10 hPa for every 100 meters of elevation.

Ex:
Elevation: 1,000 meters
Surface Pressure: 900 hPa

(1,000 meters / 100 meters) x 10 hPa = 100 hPa
SLP = 900 hPa + 100 hPa = 1,000 hPa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the difference between surface maps and upper air maps?

A

Surface Maps: identify location of lows (cyclones) & highs (anti-cyclones)
- Winds tend to flow almost parallel to isobars but do cross them
- Low pressure areas are often associated with isobar troughs (concave down)
- High pressure areas are associated with ridges (concave up)

Upper-air map: identify locations of low and high heights
- Winds flow parallel to constant height lines (height contours).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the relationship between heights on a constant pressure map and high/low pressure?

A

On a constant pressure map (e.g., 500 mb), the heights represent the altitude where that specific pressure level is reached. High heights indicate warmer, less dense air, often linked to a high-pressure system at the surface, while low heights indicate cooler, denser air, typically associated with a low-pressure system. Thus, high heights usually correspond to high pressure, and low heights correspond to low pressure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is PGF?

A

Pressure Gradient Force
The force that occurs when air flows from higher to lower pressure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is this formula and its variables?
Fx/m = (-1/p)(△P/△x)
Fy/m = (-1/p)(△P/△y)

A

Formula is for pressure gradient force.
p = density
△P = change in pressure
△x = distance in the x direction
△y = distance in the y direction

  • △x > 0 means west to east (positive x-direction)
    eastwards velocity (U component)
  • △y > 0 means south to north (positive y-direction)
    northward velocity (V component)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is CF?

A

Coriolis Force is an apparent force due to the rotation of the earth.
- Straight line motion (when observed in space) appears curved in a rotating frame.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is this formula and its variables?
Fx/m=(V)(f)
Fy/m=-(U)(f)

A

(Fx/m) x component of Coriolis Force
(Fy/m) y component of Coriolis Force

  • U (Horizontal component of velocity in the x direction)
  • V (Horizontal component of velocity in the y direction)

Coriolis parameter (f = 2Ωsin(φ))
Angular velocity (2Ω = 1.458 x 10^-4 s^-1)
Latitude (φ)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Friction Force

A
  • Friction always acts against the motion if the fluid or air. Friction acts to reduce the velocity of the wind by opposing its direction.
  • Rough surfaces tends to increase friction (ex forest and cities compared to oceans and plains)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How to convert hpa to Pa?

A

1 hpa = 100 Pa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How to convert km to m?

A

1 km = 1000 m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the origin of Geostrophic winds?

A

Above the surface, friction is minimal, leaving only the Pressure Gradient Force (PGF) and Coriolis force. When these two forces balance, the result is a steady flow that moves parallel to the isobars, known as geostrophic wind.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is Geostrophic Wind relationship to isobars?

A

Geostrophic Wind flows parallel to isobars. This occurs because the PGF acts perpendicular to the isobar, balance occurs when the Coriolis force also acts perpendicular to isobars.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Where are H/L pressure on areas on a Geostrophic wind graph?

A

Low-pressure (L) areas are on the left of the wind direction, and high-pressure (H) areas are on the right, assuming a west-to-east wind flow.
In the Northern Hemisphere, winds flow parallel to height contours (from west to east), with low heights (L) typically to the north and high heights (H) to the south.

26
Q

What is Geostrophic Flow relationship to isobars?

A

Strength of PGF and, therefore acceleration of wind, is related to spacing of isobars.
- Tightly packed = Strong Winds
- Widely spaced = Weak Winds

27
Q

What is this formula and its variables?
Ug = (1/fp)(△P/△y)
Vg = (1/fp)(△P/△x)

A

Geostrophic Wind in the x direction
Ug = (1/fp)(△P/△y)

Geostrophic Wind in the y direction
Vg = (1/fp)(△P/△x)

f = Coriolis parameter
p = density of air
(△P/△x) = Pressure Gradient
(△P/△y) = Pressure Gradient

28
Q

What is this formula and its variables? |Vg|=SQRT(Ug^2 + Vg^2)

A

The magnitude of the geostrophic wind.
Ug: the geostrophic win in the x direction
Vg: the geostrophic wind in the y direction

29
Q

How does air flow around lows and highs in both Northern & Southern Hemispheres?

A

Low Pressure Systems (Cyclones):
Northern Hemispheres: CCW around lows
Southern Hemispheres: CW around lows

High Pressure Systems (Anticyclones):
Northern Hemispheres: CW around highs
Southern Hemisphere: CCW around highs

30
Q

Why does air converge around surface low pressure and diverges away from high pressure?

A

Air converges around surface low pressure because air flows from high to low; therefore, air move towards the low-pressure center.

Air diverges around surface high pressure because air moves away from the center of the high pressure system to an area of lower pressure.

31
Q

What is the Conservation of Mass?

A

In the atmosphere, the mass of air is conserved.

32
Q

What is this formula and its variables? △p/△t=-p(△U/△x + △V/△y + △W/△z)

A

Conservation of Mass
p = density of air

Incompressibility assumption
△U/△x + △V/△y + △W/△z = 0

33
Q

What is Convergence?

A

Compression of air

34
Q

What is Divergence?

A

Spreading out of air

35
Q

Wind direction

A
  • Horizontal wind direction can also be described as an angle.
36
Q

What is this formula and its variables? |V| = (U^2 + V^2)^(1/2)

A

The magnitude (and direction) of horizontal wind V.

37
Q

What is thermal circulations?

A

In cooler regions, isobars are packed closer vertically, meaning less height is needed to reach a given pressure level, creating a horizontal pressure gradient force (PGF). Around 1 km, pressure is lower in cool air, causing air to flow from high to low pressure at that height. This results in air “piling up” above the surface in cool areas, leading to higher surface pressure, and creating a surface PGF. At the surface, air flows in the opposite direction of the flow aloft, resulting in a circulation.

This circulation is called a warm-core low/cold-core high. Thermal circulations are typically shallow (about 1 km deep) and weaken with height.

38
Q

Sea and Land Breeze

A
  • Sea breeze occurs late-morning through afternoon
  • Cooler air from ocean may act to reduce T and
    increase RH, can get clouds and precipitation
  • Given large enough regions and T differences, sea breezes can be strong, large, and travel far inland
  • Over islands or peninsulas, sea breezes from different locations can “run into” each other Sea Breeze Impacts
  • The air converges at the surface when this happens and leads to upwar motion and clouds & precip.
39
Q

Mountain and Valley Breeze

A
  • With a change in elevation, PGF also created when elevated land warms air above quicker than adjacent air over lower elevation causes higher P in valley compared to elevated slope
  • Air flows up the elevated surface, opposite at night
  • As with sea breezes, valley breezes can lead to cloud and precip. development if air is rising strong enough and air is moist enough
40
Q

Katabatic Winds

A
  • A wind flowing down from an elevated surface stronger than a mountain breeze
  • Can sometimes be exceptionally strong (hurricane-strength)
  • Snow-covered elevated sfcs. cool air above them  locally higher pressure
41
Q

Monsoon

A

A monsoon is a large-scale wind system where wind direction changes seasonally, leading to distinct wet and dry seasons. This shift causes seasonal changes in precipitation. Monsoons are driven by differential heating between land and water, similar to sea/land breezes, but on a much larger scale.

42
Q

Winter Monsoon

A

In winter, cooler air over land compared to warmer air over water creates a surface high-pressure over land. This leads to sinking air and divergence at the surface, resulting in a winter monsoon with little moisture from the ocean reaching land, leading to very little precipitation during winter.

43
Q

Summer Monsoon

A

In summer, warmer air over land compared to cooler air over water creates a surface low-pressure over land. This causes rising air and convergence at the surface, resulting in a summer monsoon where moist air from the ocean is brought over land, leading to heavy precipitation during summer.

44
Q

Three Cell Model of Earth’s General Circulation

A

Removing the “no rotation” assumption explains large-scale surface winds but not all aloft patterns. High pressure remains at the poles and low pressure at the equator. At the equator, weak PGF causes weak winds (doldrums). Air converges at the equator (ITCZ), rises, moves poleward, then sinks at 30° N/S due to Earth’s shape creating subtropical highs. Sinking air at the surface moves back towards the equator, deflected by the Coriolis effect, forming easterly trade winds.

45
Q

Where are semi-permanent Highs and Lows are and why

A

Semi-permanent Highs include Subtropical Highs near 30° latitude and Polar Highs at the poles, both caused by descending air, leading to stable, dry conditions. Semi-permanent Lows include Subpolar Lows around 60° latitude from converging air masses, and the Equatorial Low (ITCZ), where intense heating leads to rising air and frequent thunderstorms. These systems drive global weather and climate patterns.

46
Q

What are the two primary jet streams?

A

Subtropical and polar

47
Q

What is the reasons for the Polar and Subtropical Jet Streams

A

Polar and subtropical jet streams form at cell boundaries with strong temperature gradients, creating a strong pressure gradient force (PGF). The Coriolis effect deflects these winds to the right in the Northern Hemisphere, resulting in fast west-to-east winds, forming the jet streams.

48
Q

What is this formula and its variables?
A = (m)(Utot)(R)

A

Angular Momentum in a Subtropical Jet.
Utot = total eastward wind speed owning to rotation of the Earth
U = zonal wind speed and Utot is zonal speed owing to ration of the Earth
R = distance to axis of rotation

49
Q

What is Low Level Jet

A

A Nocturnal Low-Level Jet (LLJ) is a band of strong southerly winds in the Central Plains of the U.S., peaking overnight. It forms due to differential cooling between sloped terrain and flat areas, leading to a pressure gradient force (PGF) from east to west. The Coriolis force (CF) deflects this flow northward, creating the southerly LLJ. It plays a key role in fueling severe storms in spring and summer.

50
Q

What is the U.S East Coast Ocean Current?

A

East Coast dominated by Gulf Stream
Brings warm water north
Important for enhacement of low presssure systems

51
Q

What is the U.S West Coast Ocean Current?

A

West Coast dominated by cold water brought from higher latitudes

52
Q

Ekman Spiral

A

Wind imparts force on the water, water flows at angle owing to Coriolis Force
Top layer of water imparts force on layer beneath it, but CF again causes rotation to the right as flow slow

53
Q

What is Upwelling

A

Rising of cold water to the surface

54
Q

El Nino

A

increase in Eastern Pacific Sea Surface Temperature (SSTs)

55
Q

El Nina

A

decrease in Eastern Pacific Sea Surface Temperatures (SSTs)

56
Q

What is Southern Oscillation?

A

The periodic change of the PGF, the change in E and W Pacific pressures, is known as the Southern Oscillation

57
Q

What is PDO?

A

The Pacific Decadal Oscillation (PDO) is an oscillating pattern of sea surface temperatures (SSTs) in the North Pacific Ocean.

  • In the positive phase, SSTs are warm along the U.S. West Coast and cool in the central Pacific, while the negative phase is the opposite.
  • The phase changes roughly every 10-30 years.
  • The PDO significantly impacts North American winters and salmon production.
58
Q

What is NAO?

A

The North Atlantic Oscillation (NAO) is a pattern of oscillating north-south surface pressure differences over the Atlantic Ocean.

  • In the positive phase, there is a stronger south-to-north pressure gradient force (PGF), leading to stronger westerly winds.
  • In the negative phase, the PGF is weaker, resulting in weaker westerly winds.
  • The phase typically changes annually or sub-annually and significantly affects weather in the eastern U.S. and Europe.
59
Q

What are the five North American air masses?

A

cP (Continental Polar)
cA (Continental Artic)
(cP and cA bring cold, dry air from polar or Arctic regions.)

mP (Maritime Polar)
mT (Maritime Tropical)
mP and mT are moist air masses from the ocean, bringing cool or warm, humid conditions.

cT (Continental Tropical)
cT brings hot, dry air from the continental tropics, leading to dry heat in summer.

60
Q

What are the Four Types of Fronts?

A

Cold Front:
- Cold air replaces warm air.
- Sharp drop in temperature and dew point after passage.
- Winds shift from southerly to northerly.
- Causes heavy precipitation along the boundary.

Warm Front:
- Warm air replaces cooler air.
- Gradual temperature increase with widespread gentle precipitation.
- Winds shift from easterly to southwesterly.
- Precipitation forms ahead of the front.

Quasi Stationary Front:
- Little movement of air masses.
- Winds parallel the front.
- Conditions vary; may be dry or bring significant precipitation.

Occluded Front:
- Cold front overtakes a warm front.
- Creates mixed weather similar to both cold and warm fronts.
- Shown as a purple line on weather maps.

61
Q

What is Dryline?

A
  • Separates dry and moist air.
  • Found in the Southern Plains, often triggers severe thunderstorms.
  • Marked by a significant dew point drop and wind shift from SE to SW.
62
Q

Convert from knots to m s-1

A

1 knot = 1.15 mph = 0.5 m s -1

ATM 205 (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions