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158 terms


Dew is most likely to form on
Clear calm nights
All of the following is necessary for cloud formation EXCEPT
Warm surface air temperatures
Hygroscopic Nuclei
small particles on which water vapor can condense or sublime.
A cloud that forms liquid droplets has a relative humidity of 100 percent with respect to the liquid droplets. If ice crystals form in this cloud, they will experience the cloud environment as having a relative humidity
100 percent
Its raining on only one side of your street. The cloud above you is
High clouds are those that form at altitudes of at least:
above 20,000 feet
You observe a cloud at an altitude of 3000 m. This cloud name would have the prefix
Where are lenticular clouds most likely form?
on the lee side of mountains; they form whenever the airflow undulates sharpley in the veritcal.
The most common way for ait to be cooled in order that a cloud may form is by
Rising and Expanding
The important difference between liquid droplets and ice crystals in a supercooled cloud is that ice crystals
grow much more rapidly
The conditions that persist along the West Coast of the U.S. that are conducive to fog formation are
Moist air moving over a cold surface
The process by which a cloud droplet first forms is
What is the basic reason why condensation is not very important in cuasing a cloud droplet to grow to a raindrop size?
Condensation is too slow
The raindrops that fall to Earth from a warm cloud contain about one million times the water in a typical cloud droplet. This growth from cloud droplet to raindrop occurs mainly because of
Collision and Coalescence
Clouds, dew and frost all form because air has become saturated. This condition of saturation is usually caused by
Air being Cooled
When warm moist air moves over a cold surface,_____ fog may result.
Advection fog
Which type of fog occurs during nights when skies are clear and relative humidity is high?
Radiation Fog
The type of fog produced when cold air moves over a warm, moist surface is called
Steam fog
Cloud involving Thunder and Lightning
A halo around the Sun or the Moon indicates this cloud
Salt, dust particles, silver iodide, and combustion by-productions are all examples of
Condensation Nuclei
Advection fogs form best when there is no wind
A steep pressure gradient produces
Strong winds
Hydrostatic Equilibrium is best defined as
an upward directed vertical pressure gradient, which is usually balanced by gravity.
If the Earth were not rotating:
Air would move directly from high to low pressure
Meteorologists convert all atmospheric pressure data to the equivalent sea-level air pressure in order to
remove the effects of elevation
The Coriolis effect influences the wind by
Changing the direction of the wind
The Coriolis effect occurs because of this characteristic of the Earth:
its rotation
The Coriolis effect is important only for motions that
Cover long distances
The addition of water vapor will cause the density of air to
The best explanation for the cause of atmospheric pressure is
Gravity. Atmospheric pressure is the weight of a column of air. Of course, the temperatuer of that air changes its density and therefore its weight.
The effect of friction on the wind alters its
Speed and Direction
The force that generates wind is
Pressure gradient force
Geostrophic wind concept is most like the real atmospheric winds
at high altitudes
The pressure gradient force is directed from higher to lower pressure
this force is called the pressure gradient force
The primary force which causes ALL winds is
pressure gradient force
The term pressure gradient refers to
the spacing of the isobars which indicates the amount of pressure change occurring over a given distance
What do isobars represent on a map?
areas on a map of atmospheric pressure
When density remains constant and the temperature is lowered, the pressure of a confined gas
Why do surface winds cross the isobars at an angle toward lower pressure?
because of Frictional Force
According to Hadley, the most important factor causing circulation patterns in the atmosphere was
Temperature contrasts between the equator and pole
Concerning rainfall patterns, areas of persistent high pressure tend to cause
desert regions. This is because high pressure systems have sinking mechanisms, which prevent the formation of clouds and precipitation.
Dust Devils
type of microscale circulation, a well-developed vortex
El Nino events are characterized by
unusually warm ocean temperatures in the Equatorial Pacific
Most of the U.S. is situated in which zone of prevailing winds?
The term "Hadley Cell" applies to
0 deg to 30 deg latitude
Zonal refers to the east-west direction while meridional refers to the north-south direction
a CT air mass is
Continental Tropical Air; source region for cT air is the desert southwest. Skies are usually clear. This allows daytime heating during the day and radiational cooling at night.
An air mass from the Gulf of Mexico is called:
-mT; Maritime Tropical
An air mass is a body of air with
Characteristics of temperature, moisture, and pressure that are approximately uniform horizontally.
An mP air mass is
Maritime Polar; The source region for mP air is over cold ocean currents or high latitude ocean waters. Not much moisture content as cT air.
Characters of an air mass source region include
the location where the different types of air masses formed. Generally very large. Example: Ocean
Compared to continental air masses with the same air temperature, maritime air masses:
Continental tropical air masses form over tropical or subtropical water, resulting in their warm temperature. Maritime forms over Polar regions
This air mass may produce an occasional "nor'easter" in the winter
Maritime Polar
The two most important properties that should be relatively homogeneous at the same altitude in an air mass are
Temperature and amount of moisture at any given altitude.
Which of the following occurs only in summer in North America?
Maritime Polar
Which region of origin for mT air masses has the most impact on North American weather?
Western U.S.
A wind shift in a counterclockwise direction, as from east to north is
Backing wind shift
A wind shift in a clockwise direction, as from south to west is
Veering wind shift
As a warm front approaches, which progression of clouds are you most likely to see
cirrus, altostratus, stratus, nimbostratus
Tornadoes are generally associated with which type of front
A cold front moving into moist air
A trough aloft is generally associated with
Lows at the surface
A warm front is said to exist when
advancing warm air overrides retreating cold air
The lifting of air and the resulting formation of clouds and rain is more gradual for a
warm front
The more violent nature of weather produced by a cold front can be attributed to which two factors
Steep slope, fast forward motion of front
Why is the number and intensity of wave cyclones greatest during the late fall, winter, and spring months
Temperatures are below freezing
Which of these best describes the reason most high pressure systems bring clear skies?
sinking air aloft
Which of these is common to both cold and warm fronts?
lifting of warm air over cold
Compared to other types of fronts, the weather associated with a cold front usually
is more violent but of shorter duration
About how many thunderstorms take place on Earth every day?
Which of the following U.S. states experience the most thunderstorms each year?
Which of the following should have the steepest pressure gradient?
Which of the following is likely during the mature stage of a thunderstorm?
Which type of lightning is least likely?
Cloud to cloud lightning
Thunderstorms form when
Warm, humid air rises in an unstable environment
Some of the most dangerous weather is produced by a type of thunderstorm called a
Strong tornado, maximum winds approach
300 mph
Relatively narrow, elongated bands of thunderstorms that develop in the warm sector of a middle-latitude cyclone, usually in advance of a cold front
Squall lines
Fewest weather related deaths in the U.S.
What causes the dissipating stage of a thunderstorm?
spreading downdraft cuts off air flow
Why do most tornadoes in the central U.S. occur during the spring months?
Air-mass contrasts are greatest
Conventional radar measures
rainfall intensity
Why is very humid air near the surface a necessary ingredient for severe thunderstorms?
More latent heat energy available as storm
An air mass thunderstorm is most intense during
mature stage
The approximate lifetime of an individual thunderstorm cell is about
20-30 minutes
Thunderstorms are most common in
Southern Mississippi
Tornadoes are most frequent during the
Late spring and early summer when warm and cold air often clashes
Tornadoes most often move toward what direction
At what time of day is an air mass thunderstorm more likely to develop?
Mid- afternoon
Heat Lightning
Occurs more then 20km away from observer
Downdrafts totally dominate this stage of a thunderstorm
Dissipating stage
This type of cloud brings thunderstorms
Cumunolimbus clouds
If you see lightning and then hear the thunder 10 seconds later
3300 meters
How many deaths did the deadliest U.S. hurricane cause
A hurricane must have sustained wind speeds of at least
65 knots, 74 mph
Western pacific hurricanes are called
Hurricanes in the Indian Ocean
What stages do hurricanes get named
35-65 knots Tropical storm
When the entire alphabet of names is used they resort to
Greek alphabet
When winds do not exceed 37 mph
Tropical Depression
What is the single greatest advance for observing cyclones?
Satellite Imagery
Strongest category on Saffir-Simpson scale
Hurricanes often develop in late summer when waters reach
27 C
Why don't hurricanes develop near the equator
No coriolis effect
Why do surface wind speeds increase toward the center of a hurricane?
Conservation of angular momentum
Why do hurricanes in the Atlantic move toward the west during early stages?
Prevailing winds from the east
Hurricanes form in the South Atlantic
Approximate diameter of a mature hurricane
Around 300km+
Why is the eye region of a hurricane largely free of precipitation and clouds?
Subsiding air
What causes the winds of a hurricane to be so fast?
Strong pressure gradient
What part of the hurricanes produces fastest winds and storm surges?
Vertical Wall
Why do hurricanes decline over land?
Friction. lack of warm moist air
The eye of a hurricane
highest wind speeds and warmest temperature
About what percent of hurricanes that make landfall produce a tornado
Less then 1 percent
Which months do hurricanes peak in North atlantic?
This scale measures hurricane intensity
Hurricanes form in this latitude
5-20C latitude
Most important tool for detecting and monitoring hurricanes is
Doppler radar
GPS is used for
determined vertical pressure, temperature, humidity over an area
Problem with issuing a hurricane
80 to 90 percent living in these areas have not experienced a hurricane
Secondary rainbows result from
double internal reflection
How many refractions occur for a rainbow
Which of these are the primary optical phenomena causing a rainbow?
Refraction and reflection
The speed of light in water is
Fastest for red light
Rainbows are always seen with the sun
The phenomenon that results from the speed of light changing as it passes into different substances
If light enters a transparent medium at a right angle, what change occurs
Slows down, and wavelength becomes shorter
Which substance has the greatest index of refraction
Reflection, refraction, and diffraction all cause light to change its
The speed of light in space is
3 million meters per second
The property of light that causes your arm to look bent when it is submerged in water is called
The "wet area" or water surface mirage as seen on a highway occurs when
cold air is over hot water
A layer of very warm, low density air near the surface causes light to
Create an inferior mirage
Produced by refraction caused by ice crystals
Halo forms in association with
Moon and Sun
Before sunlight interacts with the atmosphere, its color is
No color
The moon appears larger when it is low on the horizon because
Optical illusion
To see a rainbow
Between the rain and the sun
Thunderstorms are electrified by
Ice particles and supercooled water form above freezing level. Negative cloud charge
Tornadoes rotate this way in Northern hemisphere
Counter-clock wise
Hurricanes re-curve because
prevailing wind and environmental flow
Hurricane in easy Asia
Hurricane in Pacific
Heat lightning is caused by
distant storms
lifetime of a single cell
20-30 mins
Maximum wind speeds ever observed in a tornado
Key ingredients that determine storm type are
moisture, lift, and instability
Squall lines form ahead of
cold fronts
El Nino is
Unseasonal warming of Pacific Ocean and area around equator
Minimum Hurricane Ocean temperature
26 C
Center of a hurricane is
Clear skies subsiding air and light winds
Hurricanes can't form along the equator because
No coriolis effect
Trade winds
South at the surface
Hurricane classifications
1. 95 2. 110 3. 130 4.155 5.156+
Wind that blows toward a Dopplar radar will shift the signal
to a higher frequency
Equatorial Orbiting Satellites
Flies along Earth's equator
Color refracted most in a raindrop
How do red and blue light differ?
Blue lights have shorter wavelength