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Atmosphere 100 Test 2

The fog that commonly forms along the West Coast of North America is ________.
advection fog
In middle and high latitudes, the most effective method of precipitation formation is ________.
the ice crystal process
Large raindrops fall ________ than smaller raindrops and have a ________ terminal velocity than small raindrops.
faster; greater
What type of precipitation would most likely form when a deep layer of air is above freezing and a shallow layer of air just above the ground is slightly below freezing?
Freezing rain.
What is sleet?
Precipitation that has frozen before it reached the ground.
Weather radar is used to identify the ________, ________, and ________ of precipitation.
intensity; location; amount
The intensity of snowfall is based on ________.
Two places at the same elevation have the same sea level pressure but at station A, the surface temperature is 5°C while at station B, the surface temperature is 20°C. If all other things remain constant, at 1000 meters above the surface, the pressure as station A would be [less/greater than or same] as the pressure station B.
less than
Low ________ on a constant elevation map corresponds to low ________ on a constant pressure map.
pressure; height
Which of the follow produces the weakest Coriolis force?

• fast winds, low latitude
• fast winds, high latitude
• slow winds, low latitude
• slow winds, high latitude
slow winds, low latitude
At your home in the Northern Hemisphere, the winds at 500mb are geostrophic and blowing from the south. With the same orientation of isobars at the [surface], the winds at your home would blow from the ________.
The amount of pressure change that occurs over a given horizontal distance is called the ________.
pressure gradient
In the Southern Hemisphere, at the surface, the wind around a high pressure area blows ________ and ________
counterclockwise and outward
A wind that blows at a constant speed parallel to straight isobars is a ________ wind.
On an upper level map, winds tend to blow...
parallel to the contour lines (whether curved or straight)
We can generally expect air to be ________ above areas of surface low pressure and ________ above areas of surface high pressure.
rising; sinking
In summer, where would you expect to find semipermanent low pressure areas?
Over land, because in summer the land tends to be warmer than the ocean.
In the three-cell model of the general circulation, areas of surface high pressure should be found at...
30° latitude and 60° latitude
The intertropical convergence zone (ITCZ) is a region where the...
northeast trades meet the southeast trades
On an upper air map, ridges are...
elongated areas of high heights.
El Niño events are marked by...
higher than normal ocean temperatures over the eastern tropical Pacific.
The most likely origin of mP (maritime polar) air masses that enter the western U.S. is
the northern Pacific Ocean
On a surface weather map, this marks the boundary where a cold, dry air mass encounters a warm, moist air mass.
Cold front
Why do we usually expect to find clouds and precipitation associated with low pressure areas, and clear skies and no precipitation associated with high pressure areas?
Because rising air is present in areas of low pressure while in high pressure areas, sinking air occurs--which doesn't produce much cloud formation.
During the ice crystal process of precipitation, ice crystals grow ________ while the surrounding liquid droplets get ________.
larger; smaller
Particles that serve as surfaces on which water vapor may condense is called...
condensation nuclei
Radar gathers information about precipitation in clouds by measuring the
amount of energy reflected back to the radar unit.
Satellite images of clouds at night use...
emitted infrared radiation.
To correctly monitor horizontal changes in air pressure, the most important correction for atmospheric pressure measurements at the earth's surface is ________.
The hydrostatic equation describes the equilibrium between the ________ and ________.
vertical pressure gradient force; gravity
Two places at the same elevation have the same sea level pressure. But at station A, the surface temperature is 8°C while at station B, the surface temperature is 18°C. If all other things remain constant, at 1000 meters above the surface, the pressure at station A would be ________ than the pressure at station B.
The contour lines drawn on a 500mb map are lines of constant ________.
The pressure gradient force is directed from higher toward lower pressure...
at all places on earth
A wind that blows at a constant speed parallel to straight isobars is called a ________ ________.
geostrophic wind
What produces the strongest Coriolis force?
Fast winds & high latitudes
We can generally expect air to be ________ above areas of surface low pressures and ________ above areas of surface high pressure.
rising; sinking
On an upper-level map (such as a 500mb map) the wind tends to blow...
parallel to the contour lines (whether curved or straight)
In summer, where would you expect to find semipermanent high pressure areas?
Over the ocean, because the ocean tends to be cooler than the land at this time of year.
In the three-cell model of the general circulation, areas of surface high pressure should be found near...
30° latitude and the poles
The polar jet stream flows
in a wavy pattern from west to east.
The most likely origin of mT (maritime tropical) air masses that enter the central U.S. is...
the Gulf of Mexico
On a surface weather map, the transition zone between two air passes with different temperature and moisture characteristics is marked by a ______.
A warm front is expected to pass Minneapolis-St.Paul by tomorrow. What is the most likely weather forecast for tomorrow?
Wind from the south, rising temperatures and increasing humidity.
This is a middle level cloud that spreads across the sky as a sheet.
A high, thin, "feathery" cloud.
An artificial cloud.
A low cloud that is associated with steady precipitation.
A very tall cloud that is producing thunder and lightning.
A halo often is associated with this cloud.
Which force causes surface winds to spiral toward the center of low pressure, but becomes insignificant as we move away from the earth's surface?
Which force initially causes the winds to blow?
Pressure gradient force
Which force depends on the speed of the earth's rotation?
Coriolis force
The warm sector of an extratropical cyclone is located ______________.
ahead of a cold front
Vorticity refers to ______.
the spin of air parcels
If the flow of air into a surface low pressure area is greater than the divergence of air above the low, the surface pressure in the center of the low will ______.
A surface high pressure system typically is located _________.
east of an upper-level ridge
Developing high pressure areas generally have ______ air near the surface and ______ air aloft.
diverging; converging
The most likely time for ordinary thunderstorms to occur is ______.
in the afternoon
What is a line of severe thunderstorms called
Squall line
Squall lines often form ahead of ______ ______.
cold fronts
Which is NOT associated with the formation of a hurricane?

• an area of low pressure
• location on the equator
• very warm sea surface temperature
• release of latent heat in tall cumulus clouds
location on the equator
Which area in the U.S. would most likely experience thunderstorms, hurricanes and tornadoes during the course of one year?
The Gulf Coast States
The forecasting technique that produces several versions of a forecast, each beginning with slightly different initial weather conditions to reflect uncertainty in the measurements is called...
Ensemble forecasting
For surface lows to persist, how do you get the necessary divergence aloft?
1. Divergence due to differences in speeds
2. Difluence where contours get far apart
for surface highs to persist, how is the convergence aloft sustained?
1. Convergence due to differences in speed
2. Confluence where contours are closer together
In the Northern Hemisphere: _______ vorticity refers to a counterclockwise spin and _______ vorticity refers to a clockwise spin.
positive; negative
A ____________ of upper-level troughs and ridges is the most favorable setting for the development of surface highs and lows.
westward tilt with height
What is cyclogenesis?
The development of cyclones.
Cold temperature advection occurs where the contours _____ the isotherms, and wind blows _____ air toward _____ areas
cross; cold; warm
No temperature advection occurs where isotherms and contours are _______ to each other.
The warm conveyor belt brings moist, warm surface air from the _____ toward the center of the low, rising up from the ________ and creating clouds and precip.
south; warm frontal surface
The cold conveyor belt brings cool (or cold) air from the _____ toward the center of the low, gaining moisture from the precip falling from the ______ above it.
east; warm belt
The dry conveyor belt brings very cold (thus--very dry) air from the ____ or _____ that spirals toward the center of the low, often creating a distinct dry slot behind the _______.
north; west; cold front
How do clouds become electrified (lightning is produced)?
Electrification results from having both ice crystals and water droplets within the same cloud--or so it is believed so far.
What is thunder?
A shockwave we hear when air expands from the intense heating caused by lightning.
What natural factors cause climate change?
Volcanoes, changes in incoming solar radiation, changes in the composition of the atmosphere, continental drift/plate tectonics, changes in the shape of the Earth's orbit (from elliptical to circular), changes in the tilt of the earth
Why does increasing atmospheric carbon dioxide concentrations lead to warmer temperatures?
Carbon dioxide absorbs infrared radiation from the sun, and in turn, the gas warms, causing the atmosphere to warm as well.
Which areas of the earth are projected to see the greatest temperature increases? Why?
The Arctic regions.
The high surface albedo of the ice allows for a gradual warming to begin with
As more and more ice melts and more land is exposed, more sunlight is absorbed and warming increases more.
Why is sea level rising?
he glaciers within Arctic regions are melting, adding more water to the oceans, and when the water with the oceans is warmed, it expands.
What is the scientific consensus on climate change?
Global temperatures are increasing, and the main cause is the increasing levels of carbon dioxide, which is mostly man-made.
Polar regions will see the most warming.
Glaciers will continue to melt, and sea level will continue to rise.
What are the sources of uncertainty in climate predictions?
Scientists are unsure how carbon dioxide emissions will change in the future.
Also, they are unsure how warmer temperatures will affect atmospheric humidity
Since water vapor is a greenhouse gas that warms the atmosphere and it's needed in cloud formation, which is needed for cloud formation.
Also, climate models are poor at handling the cloud systems and their effects.
What is a constant pressure surface?
A constant pressure surface is an area where the pressure height is constantly parallel to the surface height.
How are low and high heights related to temperature?
Low height are related to lower temperatures because cold air contracts and is closer to the surface.
High heights are related to higher temperatures because the warm air expands and rises, pushing surface pressure upwards.
How do you identify ridges and troughs?
Ridges, or elongated highs, are identified by areas of warmer air, or higher pressures.
They show up on maps as upward sloping contours.
Troughs, or elongated lows, are identified by areas of colder air, or lower pressure.
They show up on maps as downward sloping contours.
What is the pressure gradient force? In what direction does it act?
The pressure gradient force is the net force that acts upon the air between pressure differences.
It is always directed from areas of higher pressure, to areas of lower pressure.
What is the relationship between the pressure gradient force and wind speed?
The greater the PGF, the greater the wind speeds, and vice-versa.
What is the Coriolis force? In what direction relative to the flow does it act in the Northern Hemisphere?
The Coriolis force is an apparent force that is due to the rotation of the Earth.
It causes all free-moving objects, such as ocean currents, aircraft, artillery projectiles, and air molecules to appear to deflect from a straight-line path due to the Earth's rotation beneath them.
In the Northern hemisphere, the free-moving object appear to veer to the right.
How does the Coriolis force depend on wind speed?
Faster winds cause a stronger Coriolis force, and vice-versa.
Does the Coriolis force influence the direction a toilet flushes? Why or why not?
No. The Coriolis force is so small in comparison to all other forces in our everyday experiences that it is negligible.
How do you determine the upper-level winds given height contours?
Winds aloft on an upper-level chart tend to blow more or less parallel to isobars.
How do you determine the pressure gradient and Coriolis forces from height contours on an upper-level map?
he PGF always runs from areas of high pressure to areas of low pressure.
The Coriolis force is always at a 90 degree angle to the wind direction. (see lab 7)
What is the geostrophic wind?
Winds aloft that blow parallel to isobars
What is gradient wind balance? When does it apply?
Gradient wind is a wind that blows at a constant speed parallel to curved isobars above the level of frictional influence.
It applies when the PGF balances the Coriolis force, causing the net force (acceleration) to be zero.
How does the wind aloft around highs and lows compare to the geostrophic wind?
Around lows, the PGF is directed towards the center of the low, and the net force has to be directed inward toward the center of the low.
Centripetal force causes the wind to blow around the low (counterclockwise and inward).
The PGF is greater than the Coriolis force around a low.
Around highs, the PGF is directed away from the center of the high, and the net force must be directed inward toward the high.
Centripetal force causes the wind to blow around the high (clockwise and outward).
The Coriolis force must be greater than the PGF around highs.
What is a cyclone? An anticyclone?
A cyclone is a low pressure that the air moves counter-clockwise around (in the NH), and is called cyclonic flow.
An anticyclone is a high pressure system that the air moves clockwise around (in the NH), and is called anticyclonic flow.
What force is important at the surface that is not important aloft?
What is friction? What does it do?
Friction is the drag of the wind caused by the ground. It makes surface winds cross isobars and blow more slowly than the winds aloft.
It does this because it reduced windspeed, in turn, reducing the Coriolis force.
How do you determine the surface wind pattern from isobars?
The surface wind flows clockwise and outward around a high pressure system, and counterclockwise and inward around a low pressure system.