Test: Weather Flashcards
what two things classify an air mass?
temperature and amount of moisture
define an air mass.
air mass- a large body of air with similar characteristics throughout.
define front.
when two air masses meet & form a border
what is a cold front?
when a cold air mass meets a warm air mass
what type of weather do cold fronts bring?
rain develops and thunderstorms occur.
what is a warm front?
when a warm air mass catches up to a cold air mass.
what kind of weather do warm fronts bring?
clear skies
what is a stationary front?
a front that stops moving.
what time of weather do stationary fronts bring?
causes constant snow or rainfall leading to several inches of snow or it could even cause a flood.
what symbol is used for warm fronts?
red, semi circles
what symbol is used for cold fronts?
blue, triangles
what are the lines in a pressure diagram called?
isobars
winds always blow from ________.
high pressure to low pressure
what is the instrument that measures air pressure?
barometer
how does a barometer work?
when the mercury is high, there is high pressure. when the mercury is low, there is low pressure
what direction do polar easteries blow?
east to west
what direction do the westerlies blow?
west to east
what zone is windless?
the doldrums
polar easterlies have the strongest winds because of the __________
Coriolis effect
relative humidity is relative to ____________.
what’s happening in the atmosphere
which is more active? relative humidity or dew point?
dew point
what is water that evaporates from the leaves on trees?
transpiration
what is condensation?
water droplets forming together
what is evaporation?
water turning into a gas and rising into the atmosphere
how does a front create pressure?
they bring clouds and precipitation that affect the pressure.
what is the coriolis effect?
the apparent deflection of objects moving in a straight path relative to the earth’s surface
how does the Coriolis effect create wind?
the spinning of the earth in relation to the gas molecules creates wind
describe the trade winds
air movement towards the equators, caused from cold air sinking and warm air rising, Coriolis effect makes the trade winds appear to be curving to the rest
describe the prevailing westerlies
winds are named from the direction in which they originate, between 30-60 degrees latitude
what are isobars?
lines that show pressure.
how do you know if the winds will be fast or slow?
the closer together the lines are, the faster the winds are. the farther they apart, the slower the winds are.
what is the difference between relative and absolute humidity?
relative humidity is the percent of water in the air compared t how much it can hold, and absolute humidity is the exact physical amount of water in the air.
what is dew point?
the temperature at which air can longer “hold” all of the water vapor and it condenses to liquid form
when will dew point be higher?
when there is more water in the air
what type of weather is expected in a low pressure system?
bad weather- precipitations, produces clouds, tropical storms and hurricanes
what type of weather is expected in a high pressure system?
clear skies and calm weather
what is a tornado?
a violent windstorm that takes the shape of a column of air during a severe thunderstorm
when are tornadoes most common?
spring; May is the most common month
why are tornadoes most common in the United States?
because of our unique geography (humid, hot air rising north that collides with cold, dry air moving south)
what scale is used to measure tornadoes?
the Fujita intensity scale
what could happen if someone experiences an F-1 tornado?
chimneys could be damaged, tree branches would break, and shallow-rooted trees would topple.
what could happen if someone experiences an F-5 tornado?
houses can be lifted from foundation, trees are completely debarked, automobile-sized debris becomes airborne
how fast does wind have to be blowing to be considered a hurricane?
at least 74 mph
where do hurricanes form?
over very warm ocean water
when are hurricanes most common?
in September because ocean waters are warmest
what is the calmest part of a hurricane called?
the eye
where is the heaviest wind and rain in a hurricane?
the eye wall
what scale is used to classify a hurricane?
the saffir-simpson scale
compare a category 1 hurricane to a category 5 hurricane.
- category one: coastal flooding, damages unanchored mobile homes
- category five: complete building failures, all trees blown down
what is the difference between a cyclone and an anticyclone??
an anticyclone is a high pressure system and a cyclone is a low pressure system.
what is an occluded front?
a boundary between cool, cold and warm air masses.
When it is hot enough, most water molecules will be in ______ form in the atmosphere.
Gas
How much of the sun’s energy warms the land and oceans?
Four tenths
What is the main cause of the coriolis effect?
Earth’s rotation; counter clockwise on its axis
What is pressure in the atmosphere measured in?
Millibars (mb)
What is pressure?
Force per unit of area exerted on the Earth’s surface by the weight of the air above the surface
What two things are pressure associated with?
Weather patterns and wind
Air masses form over _____ and dry air masses form over _____.
Water, land
