Exam 2

Question 1

What is the equilibrium vapor pressure?

Answer 1

Another way of expressing saturation vapor pressure. Indicates the evaporation rate of a liquid.

Question 2

How do the curvature and solute effect work?

Answer 2

Curvature: states that water evaporates easier from a curved surface (requires higher saturation vapor pressure to maintain a state of equilibrium). Requires supersaturation to maintain cloud droplet

Solute: condensation nuclei are hygroscopic (water attracting) which allows condensation at RH well below 100%. Liquid water forms with condensation nuclei, making it harder to evaporate the liquid water (solid will dissolve in water which makes the water not want to evaporate)

Question 3

How does collision-coalescence work?

Answer 3

Droplets of different sizes colliding and coalescing (combining) to form larger droplets. Think of when water droplets on a windshield fall down and they combine into nearby droplets to form a bigger droplet. The reason why rain doesn’t hurt us is because of its terminal velocity (gravity is balanced by frictional drag).

Question 4

How does the Bergeron process work?

Answer 4

The formation of ppt in middle and high latitudes in clouds at or below freezing. These clouds have to be a mixture of both ICE and WATER, and if the cloud is purely ice the process will not work as well. These ice crystals grow through the surrounding water droplets.

Question 5

What is supercooled liquid water?

Answer 5

Water at temperatures below freezing, but above -40 C. The less pure the water is, the lower the freezing point. Very small droplets freeze at much lower temps.

Question 6

What are ice nuclei?

Answer 6

Very rare formation where it allows direct deposition of water vapor. It has to favor 6-sided formation.

Question 7

What are accretion and aggregation and their importance to ice crystals?

Answer 7

Accretion (graupel): Some supercooled liquid water possibly colliding with ice crystals, freezing it to the ice

Aggregation: ice crystals colliding and sticking together (really only effective above -10 C).

Question 8

What are the different types and terminology of ppt?

Answer 8

Rain: falling drop of liquid water

Drizzle: raindrops less than 0.5 mm

Virga: rain that evaporates before reaching the ground (now really ppt)

Cloudburst: intense and brief rain shower (microbursts are different by being more about the WINDS)

Snow: frozen water falling from the sky (crystal or flake)

Fallsteaks: ‘virgia’ but with frozen ppt that evaporates/ sublimates before hitting the ground. Will appear darker

Flurries: light snow, often non-accumulating

Snow squall: intense but brief period of snow

Thundersnow: snow falling from intense cumuliform clouds producing thunder and lightning

Blizzard: low temps and strong winds with large amounts of fine, dry, powdery snow, but not necessarily heavy snow

Sleet: snow forming in air below freezing. Travels through a layer of air above freezing and begins to melt. It then falls through air below freezing just above the ground surface and refreezes immediately. NOT A RAIN/SNOW MIX. SMALL PELLETS OF ICE

Freezing rain: unlike sleet, the cold surface layer is not thick enough to refreeze ppt. Liquid hits the surface and quickly freezes.

Freezing drizzle: Freezing rain but droplets are less than 0.5 mm

Snow grains: Very small (<1 mm), white, opaque grains of ice that are fairly flat or elongated. Unlike snow pellets, snow grains do not bounce or break up on impact.

Snow pellets: White and opaque ice particles that are generally conical or rounded, and their diameter may be as large as 5 mm.

Hail: Graupel (accretion of ice and water colliding) an an embryo in intense. Grow as pushed up by updraft (layered).

Question 9

Study the vertical processes of sleet, snow, and freezing rain and describe them

Answer 9

No :) (https://cdn.discordapp.com/attachments/1048318325043761293/1088560801989787648/image.png)

Question 10

What is the ideal gas law in relation to temperature, pressure, and density?

Answer 10

Density is inversely related to temp at same temperature.

Cold air –> more dense
Warm air –> less dense

Question 11

What is station pressure? What is sea level pressure?

Answer 11

Station pressure: pressure measured at a station

Sea level pressure: constant height (a comparable pressure value)

Question 12

How is pressure displayed on upper-level (isobaric) charts?

Answer 12

Chart is drawn on a constant pressure surface (250 mb, 500 mb, etc). It uses isobars to show how the pressure changes at certain locations at different altitudes.

Question 13

How do variations in temperature create variations in upper-level isobaric charts?

Answer 13

On a constant pressure surface, warmer, less dense air have higher heights on isobaric charts; colder, more dense air have lower heights.

Question 14

What are ridges and troughs? What do they look like in both the northern and southern hemisphere? What are their connections to warm and cold air?

Answer 14

Ridge: an elongated area of high pressure

Trough: an elongated area of low pressure

In the NORTHERN hemisphere, troughs are u shaped. Ridges are n shaped

In the SOUTHERN hemisphere, troughs are n shaped. Ridges are u shaped.

(In the US) troughs bring cold air from Canada. Ridges bring warm air from the Gulf.

Question 15

What are cyclones and anticyclones? What are their characteristics?

Answer 15

Cyclones: low pressure. Counterclockwise in NH (clockwise in SH). Clouds and ppt.

Anticyclones: High pressure. Clockwise in NH (counterclockwise in SH). Clear and no ppt

Question 16

please 4 the love of god look at the wind vector thingy. ykno the thing with the arrows pointing in different directions with pressure gradient force, Coriolis force, centripetal force, and friction????????? yea pls look at this istg. in BOTH hemispheres

Answer 16

okay but what if i didnt

Question 17

What is the Coriolis force, and how does it differ in the NH and the SH?

Answer 17

Deflection of objects due to rotation of the Earth. In the NH it deflects RIGHT. In the SH it deflects LEFT.

Question 18

What is Newton’s first law of motion and how does it relate to atmospheric motions?

Answer 18

An object at rest will remain at rest, and an object in motion will remain in motion as long as no force is executed on the object (F=ma). It relates to atmospheric motions by acceleration such as the pressure gradient force, Coriolis force, friction, and centripetal accelerations.

Question 19

What are geostrophic and gradient winds? Where are they found (surface/ aloft/ both)? What conditions are necessary for their formation? What forces come into balance in each? What forces play a role in surface winds?

Answer 19

Geostrophic: Constant speed. Aloft. Forms by the PGF moving from high to low pressure, and the Coriolis force deflecting opposite to it. Geostrophic winds move tangent to these forces, following parallel to isobars. The pressure gradient force and the Coriolis force balance each other out.

Gradient: Constant winds blowing parallel to curved isobars. No friction. Only Coriolis force, pressure gradient force, and centripetal force.

Surface: Pressure gradient force, Coriolis force, friction

Question 20

What is meant by meridional and zonal flow?

Answer 20

Meridional: Wind flowing in a N/S pattern

Zonal: wind flowing parallel to lines of latitude, or are a more W/E pattern

Question 21

What are the vertical air motions associated with high and low pressure centers?

Answer 21

Low: Air rises. If surface convergence is greater than divergence aloft, will weaken. If divergence aloft is greater than convergence at surface, will strengthen. Convergence at SURFACE. Divergence ALOFT.

High: Air sinks. Divergence at SURFACE. Convergence ALOFT.

Question 22

What are the scales of atmospheric motion? What are their approximate time and spatial scales?

Answer 22

Microscale: Less than a few meters; minutes to seconds; eddies

Mesoscale: 2-100 km; thunderstorms/ tornadoes; land/ sea breezes, mountain/valley breezes; minutes to days

Synoptic scale: high/ low pressure; hurricanes; fronts; days to weeks

Global scale: long/rossby waves; global circulation cells

Question 23

What is the difference between mechanical and thermal turbulence? What conditions lead to strong turbulence (each individually, or both together)?

Answer 23

Mechanical: Variations in terrain and surface roughness generate eddies; wind gusts.

Thermal: Strong heating causes vertical air motions; may extend through the troposphere. Strongest by mid-day (warmest)

Surface heating, strong wind speeds, and rough/ hilly terrain can lead to strong turbulence.

Question 24

What are eddies?

Answer 24

Atmospheric turbulence

Question 25

What is, and how high is, the planetary boundary layer?

Answer 25

The planetary boundary layer (PBL) is the layer near the surface of the Earth where wind is affected by friction. It is 1 km high/deep

Question 26

How are winds defined/ described?

Answer 26

Direction (from which it is blowing)

Speed/ velocity

Gustiness

Question 27

What is meant by prevailing winds, and how are these generally determined (i.e., what plot or graph would help us see the prevailing wind)?

Answer 27

The wind direction that is frequently observed during a time period. This is determined by a wind rose

Question 28

What are thermal circulations, and what drives them initially?

Answer 28

Heating and cooling of the atmosphere above the ground create cold high and warm low pressure cells. They’re initially driven by wind travelling from a high pressure cell to a low pressure cell.

Question 29

What are land and sea breezes at the surface and aloft? How do they change from day to night?

Answer 29

Land: In the day, warm air from land blows into the sea. At night, the cooler land blows onto sea.

Sea: In the day, cool air blows onto land. At night, warm air blows onto land.

Question 30

Where in the U.S. do sea breezes have a significant impact, and why?

Answer 30

Coastlines near large bodies of water because their closeness to the water.

Question 31

What is meant by a monsoon circulation, and where are they common?

Answer 31

A monsoon is a seasonal change in the direction of the prevailing, or strongest, winds of a region. They’re most common eastern India and SE Asia

Question 32

What are katabatic, Chinook, foehn winds? What makes the Chinook wind warm, and how might precipitation on the windward side of the mountain range influence the intensity of a Chinook wind?

Answer 32

Katabatic: Heavy, dense, cold wind rushes down evaluated slopes (usually weak).

Chinook: Dry, warm air descending on the leeward side of an orographic barrier. Eastern slope Rockies. It warms up after descending off of leeward side.

Foehn: Dry, warm air descending on the leeward side of an orographic barrier. Europe.

Question 33

What are Santa Ana winds? How do they form, and where are they common?

Answer 33

A warm, dry wind that blows downhill from the east or northeast into southern California. These warm, dry winds develop as a region of high pressure builds over the Great Basin.

Question 34

What are semi-permanent pressure systems? In what season are some of these semi-permanent pressure systems marked?

Answer 34

Systems that barely move throughout the year. They’re marked in summer.

Question 35

What are the names and approximate location of some major semi-permanent pressure centers in the NH?

Answer 35

Aleutian Low: Along the Aleutian Islands

Icelandic Low: Between Greenland and Iceland in Atlantic

Hawaiian High: Over Hawaii

Bermuda High: Slightly west of Spain/Portugal

Canadian high: Over southern Canada/ very north USA

Siberian High: Primarily over Russia/ Asia continent

Mascarene High: West of Australia/ just east of South Africa

Question 36

How does the general circulation influence global precipitation patterns?

Answer 36

Areas where low pressure systems dominate will typically receive more ppt while areas where high pressure systems dominate typically don’t

Question 37

How do the pressure patterns vary by latitude aloft?

Answer 37

In July, the winds are seen to be more easterly at the equator. Winds are faster aloft in the winter. idc to put more

Question 38

What are jet streams?

Answer 38

Fast winds at high altitudes; are thousands of km long and several 100 km wide

Question 39

What are the key features of the subtropical and polar front jet? Where are they located (in latitude approximately) and in the 3-cell model?

Answer 39

Subtropical: ~30 degrees N/S SUMMER. Hadley cell

Polar: 40-60 degrees N/S WINTER. Polar front/ ferrel cell

Question 40

What factors lead to the formation of the two jets?

Answer 40

Steep temperatures and pressure gradients between circulation cells

Question 41

Explain the concept of conservation of angular momentum, and particularly, how it relates to the strength of the subtropical jet.

Answer 41

It is the driver of the subtropical jet. As air rises poleward, the radius (r) decreases. This causes the speed of air to increase as it continues poleward.

Question 42

What are air masses and source regions? What two variables are used to classify air masses?

Answer 42

Air masses are extremely large bodies of air where temperature and humidity are similar horizontally and vertically. Classified by both moisture (m or c) and temperature (P;T;A;E)

Source regions: area where air mass originates; usually flat and uniform composition with light surface winds.

Question 43

Know the main types of air masses, their source regions, and key features of each

Answer 43

cP and cA: N Canada, Alaska (dry, cold, stable –> cA more extreme)

mP: North Pacific, North Atlantic (cool, humid, unstable)

mT: Gulf of Mexico, S Atlantic, Caribbean, SE Pacific (wet, warm, unstable; most moisture and near subtropical high; atmospheric rivers)

cT: SW US, Mexican Plateau (hot, dry, conditionally unstable)

Question 44

What are fronts, and what features are used to identify them on weather maps?

Answer 44

Transition zone between two air masses of different densities. Features used to identify them are blue triangles, red half-circles, combination of triangles and half circles that are alternating, and purple triangles and half circles.

Question 45

What are the main types of fronts, what types of weather are expected with them, how steep their vertical slopes (qualitatively) are, and how winds are generally orientated behind and in front of them

Answer 45

Stationary front: no movement. Variable weather. Parallel but opposite wind.

Cold front: Cold, dry stable air (cP) replaces warm, moist unstable air. Winds have a southerly component ahead and westerly behind. Clouds are very steep. Thunderstorms, squall lines

Warm fronts: warm, moist unstable air overrides cold, dry stable air. Horizontal cloud development with steady rain, weak slope (stratus). Typically easterly component to winds ahead of front, southerly behind front. Frontal inversion almost always (warm air over cold)

Occluded: Cold front catches up to and overtakes a warm front. Warm air is cut off from the surface.

Question 46

What is the difference between a warm and cold occlusion?

Answer 46

When the air behind the front is colder than the air ahead of it, the front is called a cold
occlusion.

When the air behind the front is milder than the air ahead of it, it is called a warm occlusion.