|
El Niño events are characterized by |
pooling of unusually warm water in the eastern tropical Pacific. |
|
The greater strength of jet stream winds during winter is due to |
greater horizontal temperature contrasts. |
|
Which of the following is an example of a mesoscale wind? |
a sea breeze |
|
Concerning rainfall patterns, areas of persistent high pressure tend to cause |
desert regions. |
|
The primary force which causes all winds is |
pressure gradient force. |
|
You would expect vertical airflow in an anticyclone to result in |
convergence aloft. |
|
When are upper air winds fastest? |
in winter |
|
The definition of the word ‘monsoon’ means |
seasonal wind shift. |
|
The cyclones and anticyclones of the midlatitudes are part of the ________ circulation. |
synoptic or macroscale |
|
Instead of the air flowing straight out of a high pressure system, it spirals out in a clockwise direction. The cause of the clockwise spiraling motion is |
coriolis force |
|
If the earth were not rotating, |
air would move directly from high to low pressure. |
|
The subpolar low (polar front) is |
a zone where the polar easterlies and the westerlies converge. |
|
The major features of precipitation distribution patterns are determined by |
general circulation and pressure patterns. |
|
Cyclonic airflow is characterized by |
divergence aloft and convergence at the surface. |
|
The effect of friction on the wind alters its |
speed and direction. |
|
Most of the United States is situated in which zone of prevailing winds? |
westerlies |
|
The region where the northeast trades meet the southeast trades is known as the |
ITCZ. |
|
Circulations in the earth’s atmosphere are fundamentally caused by |
temperature contrasts between different locations. |
|
A steep pressure gradient |
produces strong winds. |
|
The pressure gradient force is directed from higher to lower pressure |
everywhere. |
|
When air moves from the ocean onto land |
converging winds and ascending air result over the land. |
|
The Sahara and Australian deserts (among others) are associated with which pressure belt? |
subtropical high |
|
The areas of abundant rainfall on the earth tend to be |
near the equator and in midlatitudes. |
|
High air pressure zones are usually associated with |
relatively dry conditions. |
|
A primary factor causing monsoon circulations is |
greater temperature changes over continents compared to oceans. |
|
Upper air winds |
are generally faster than surface winds. |
|
Horizontal variations in air pressure cause a force which makes the wind blow. These pressure variations are caused by |
uneven heating of the earth’s surface. |
|
The amount of precipitation received at a given location is primarily controlled by |
circulation patterns in the atmosphere. |
|
Microscale winds generally last for |
a few seconds. |
|
Which of these factors influence the magnitude of the Coriolis force? |
both wind speed and latitude |
|
A Santa Ana (or Chinook or Foehn) wind is a |
very dry, warm wind coming down a mountain slope. |
|
In the northern hemisphere, cyclonic winds flow |
inward and counterclockwise. |
|
The geostrophic wind concept is most like the real atmospheric winds |
at high altitudes. |
|
Taken as a whole, the large scale or general circulation patterns of the atmosphere exist |
as nature’s method of balancing heat energy differences. |
|
The Coriolis effect is important only for motions that |
cover long distances. |
|
You would expect vertical airflow in a cyclone to result in |
divergence aloft. |
|
The best explanation for the cause of atmospheric pressure is |
weight of the air above. |
|
Most of the earth’s deserts are located in the |
subsidence areas of subtropical highs. |
|
Winds are usually named for |
the direction or place from which they are blowing. |
|
The process that brings cold, nutrient-rich water to the surface along the coasts of Peru and Ecuador is called |
upwelling. |
|
Jet streams are associated with fronts because of the |
large temperature gradient. |
|
The Coriolis effect occurs because of this characteristic of the earth |
its rotation. |
|
What option below best characterizes the rainfall distribution at a station located on an island in the Arctic Ocean at about 80 degrees N latitude? |
dry all year around |
|
The force that generates wind is |
pressure gradient force |
|
Meteorologists convert all atmospheric pressure data to the equivalent sea-level air pressure in order to |
remove the effects of elevation. |
|
The overall strength of a circulation system is determined by |
its pressure gradient. |
|
The wind speed normally increases with height in the layer of air next to the ground. This illustrates the fact that |
friction is present only close to the ground. |
|
Air Pressure |
the pressure exerted by the weight of air |
|
How is air pressure exerted? |
in all directions |
|
the air pressure pushing down on an object exactly balances________ |
the air pressure pushing up on the object |
|
What is a barometer? |
a device used for measuring air pressure |
|
How does a barometer measure air pressure? |
when air pressure increases, the mercury in the tube rises. When air pressure decreases, so does the height of the mercury column |
|
What three factors combine to control wind? |
pressure differences, the Coriolis effect, and friction. |
|
what two terms have to do with pressure differences? |
pressure gradient and isobars. |
|
What is a pressure gradient? |
the amount of pressure change occurring over a given distance. |
|
What are isobars? |
lines on a map that connect places of equal air pressure. |
|
What do they indicate? |
they indicate a steep pressure gradient and high winds. |
|
Widely spaced isobars indicate_______ |
a weak pressure gradient and light winds. |
|
Isobars where the air pressure number is the highest in the middle show______ |
anticyclones |
|
Isobars that have the lowest air pressure number in the middle show_______ |
cyclones |
|
What is the Coriolis Effect |
the Coriolis effect describes how Earth’s rotation affects moving objects. |
|
What happens in the northern hemisphere in the Coriolis Effect? |
all free-moving objects or fluids are deflected to the right of their path of motion |
|
and the southern hemisphere? |
all free-moving objects or fluids are deflected to the left of their path of motion. |
|
What is friction? |
friction acts to slow air movement, which changes air direction. |
|
What are jet streams? |
fast moving "rivers of air |
|
Jet streams travel in a ____ to _____ direction |
east to west |
|
Jet streams travel between ___ and ___ ____ |
120 and 240 kmph |
|
What are cyclones? |
centers of low pressure |
|
What are anticyclones? |
centers of high pressure |
|
When the pressure gradient and the Coriolis effect are applied to pressure centers in the Northern Hemisphere_______ |
winds blow counterclockwise around a cyclone and clockwise around an anticyclone. |
|
What happens in the southern hemisphere? |
winds blow counterclockwise around an anticyclone and clockwise around a cyclone |
|
In either hemisphere, friction causes a netflow of air inward around a(n)_____ and a net flow of air outward around a(n)______ |
1. cyclone 2. anticyclone |
|
What is rising air associated with? |
cloud formation and precipitation (rain, snow, sleet, hail, etc) |
|
What is sinking air associated with? |
clear skies |
|
Low-Pressure centers (cyclones) produce_____ |
bad weather in any season |
|
High-Pressure centers (anticyclones) produce____ |
nice (fair) weather in any season |
|
What is the Non-Rotating earth model? |
On a hypothetical non-rotating planet with a smooth surface of either all land or all water, two large thermally produced cells would form. |
|
What are two important things to remember about the non-rotating earth model? |
1. It is HYPOTHETICAL!!! 2. the earth would need to be made of ALL land or ALL water. |
|
What is the problem with the non-rotating earth model |
some areas would be freezing because of no sunlight and other areas would receive too much sunlight. |
|
Name the 4 global wind types |
trade winds, westerlies, easterlies, polar fronts |
|
What is a polar front? |
a stormy frontal zone separating cold air masses of polar origin from warm air masses of tropical origin. |
|
What is a monsoon? |
the seasonal reversal of wind direction associated especially with Asia. |
|
In the winter, the wind blows from ____ to ___ |
land to sea |
|
In the summer, the sea blows from ___ to ____ |
sea to land |
|
What are local winds? |
winds that are caused either by topographic effects (mountains, valleys, etc.) or by variations in surface composition (land and water) in the local area |
|
What are land and sea breezes like in the day? |
in coastal areas during the warm summer month, in the day the air moves from high pressure to low pressure. The high pressure is the water and the low pressure is the land. So in the day, wind moves from sea to land. |
|
What are land and sea breezes like in the night? |
the land cools faster than the water at night so the air moves to the warm water making the wind blow from land to sea at night. |
|
What are valley and mountain breezes? |
the air on the slopes of the mountain is heated more intensely than the air at the same elevation but at the valley floor. The air on the slopes is less dense so it glides up the slope and generates a valley breeze. The pattern may reverse after sunset. |
|
What are prevailing winds? |
winds that blow more often from one direction than from any other. |
|
What is an anemometer? |
an instrument that resembles a cup and is commonly used to measure wind speed. |
|
What is El Niño? |
the periodic warming of the ocean |
|
Where does El Niño occur? |
in the central and eastern Pacific |
|
What happens at irregular intervals of three to seven years? |
the warm countercurrents become unusually strong and replace normally cold offshore waters with warm equatorial waters. |
|
What can a major El Niño cause? |
Extreme weather in many parts of the world and the loss of many fish. |
|
What is La Niña? |
the name for when the temps. in the eastern pacific are colder than average. |
|
La Niña has___ |
a distinctive set of weather patterns. |
|
4 forces that cause the wind. |
Horizontal Pressure Gradient Coriolis Centripetal Friction |
|
Pressure gradient equation |
Pressure gradient = change of pressure(millibars)/distance(meters) |
|
Forces that influence air flow ALOFT |
Pressure gradient force. Directed perpendicular to isobars from H to L. |
|
Coriolis Force |
Apparent deflection of winds due to earth’s rotation. |
|
The Coriolis force deflects winds to the _____ in the northern hemisphere and to the ______ in the southern hemisphere. |
right, left |
|
With respect to the Coriolis Force, the stronger the winds, the _____ the deflection |
Greater |
|
There is no Coriolis effect at the ______. |
Equator |
|
Coriolis force effects ______ but not ______. |
direction speed |
|
Coriolis force only has significant impact over ______ distances. |
Long |
|
Coriolis force _______ while approaching the poles. |
Increases |
|
Geostrophic winds: |
Wind that results from the theoretical geostrophic balance. Flows directly parallel to isobars. Helps us understand the winds aloft. Known as earth turning winds. |
|
Geostrophic balance |
Where the Coriolis effect is equal to the pressure gradient force. |
|
The speed of the geostrophic winds are directly related to the pressure gradients. |
Bernoulli’s principle. High pressure = slow speed. Low pressure = high speed. Boats crashing. |
|
Cyclonic winds are ______ in direction in the northern hemisphere. |
Counterclockwise |
|
Anticyclones are ______ in direction in the northern hemisphere. |
Clockwise. |
|
Cyclones are ______ in direction in the southern hemisphere. |
Clockwise. |
|
Anticyclones are ________ in direction in the southern hemisphere. |
Counterclockwise. |
|
For surface winds, ______ reduces wind speed which in turn reduces the ______ effect. |
friction coriolis |
|
Surface winds cross isobars at approximately __ degrees into low pressure and out of high pressure. |
30 |
|
Vertical motion associated with cyclonic motion |
Rising |
|
Vertical motion associated with anticyclonic motion |
Subsidence |
|
Motion associated at the top of a low pressure system |
Divergence |
|
Motion associated with the top of a high pressure system |
Convergence |
|
Wind is characterized by _____, _______, and ______. |
Direction, speed, and gustiness. |
|
Wind direction describes the direction ______ which wind is blowing. |
from |
|
Prevailing winds are |
the winds that blow with respective direction in each cell, or section of latitudes. e.g westerlies |
|
Air Pressure |
The pressure exerted by the weight of air above a given point. It is measured in mb, inches or kPa. Low pressure is associated with disturbed weather (rain). It is measured differently in various countries. |
|
High Air Pressure |
The higher the reading, the greater the chance of clear weather. It has sinking air and clouds are unable to form. It is indicated by sunny days and clear night skies. |
|
Low Air Pressure |
The lower the reading, the greater the chance of inclement weather. It has rising air and is indicated by a cloudy sky and precipitation. |
|
Barometer |
Measures air pressure. |
|
Mercury Barometer |
Measures air pressure with mercury. When air pressure is high, the mercury level rises. |
|
Pressure Gradient Force |
The movement of air from high to low pressure proportional to the pressure gradient. |
|
Pressure Gradient |
The rate of decrease of pressure per unit of horizontal distance. Strong ones are indicated by closely spaced isobars. |
|
Isobar |
A line of equal air pressure (every location along that line has the same air pressure). Used on surface weather maps to show air pressure. |
|
Surface Weather Map |
A map that shows the distribution of sea-level pressure with isobars and weather phenomena. Purple arrows show flow of wind. |
|
Isoheight |
The height in metres that one must travel upward to reach the 500 mb pressure level. Air pressure on upper-level weather maps is labelled using this. |
|
Ridge |
An upward bend in the isoheights around high pressure. |
|
Trough |
A downward bend in the isoheights around low pressure. |
|
Upper-level maps |
Needed to forecast the weather because upper-level winds help us determine the movement of surface weather systems and whether surface systems will intensify or weaken. |
|
Coriolis Force |
A force resulting from the rotation from the Earth. It causes wind to deflect to the right in the northern hemisphere and the left in the southern hemisphere. As wind speed increases, this increases. This increases with distance away from the equator. |
|
Geostrophic Wind |
Blows straight and parallel to isoheights. When the Coriolis Force exactly balances the PGF, this results. |
|
Meridional Flow |
Wind flowing in a large, looping meanders. |
|
Zonal Flow |
Wind flowing in a general west-to-east direction. Weather systems move more quickly during this. |
|
Centripetal Force |
The radial force required to keep an object moving in a curved path. It is an inward directed force toward the centre of rotation. It causes wind to blow around highs and lows in a circular motion. |
|
Cyclonic Flow |
The circulation of air around low pressure. |
|
Anticyclonic Flow |
The circulation of air around high pressure. |
|
Northern Hemisphere Air Flow |
Wind always blows clockwise around high pressure and blows counter-clockwise around low pressure. |
|
Southern Hemisphere Air Flow |
Wind always blows counter-clockwise around high pressure and blows clockwise around low pressure. |
|
Frictional Force |
A force at the surface resulting from mountains, trees, buildings, etc. Acts directly against the flow of air leading to a reduction in wind speed. Coriolis force is also reduced. |
|
Cross-Isobaric Flow |
The wind blows at a 30 degree angle across isobars causing the wind at the surface to blow inward. This resulted from frictional force. |
|
Buys-Ballot Law |
If the direction of the wind is known, the general location of pressure systems may be determined by standing with your back to the wind. Lower pressure is then to your left. |
|
Convergence |
An atmospheric condition that exists when the winds cause a horizontal net inflow of air into a specified region. |
|
Hydrostatic Equilibrium |
The state of the atmosphere when there is a balance between the vertical pressure gradient force and the downward pull of gravity. |
|
Azimuth |
Wind is reported from the direction that it originates. |
|
Wind Rose |
A diagram indicating including the prevailing wind of a location. |
|
Prevailing Wind |
The wind direction most often observed. In most of North America it is westerly. It plays a role in urban planning and may be noticeable by the appearance of trees. |
|
Tacoma Narrows Bridge Collapse |
In 1940, high winds cause the collapse of a suspension bridge in Tacoma, Washington. The design of the bridge did not provide any open trusses for wind to pass through. |
|
Wind Vane |
An instrument used to determine wind direction. |
|
Anemometer |
An instrument used to measure wind speed. |
|
Aerovane |
An instrument that indicates both wind speed and direction. |
|
Wind profiler |
A record used to assist in determining wind shear. |
|
Wind shear |
A change in the direction or speed of the wind over a horizontal or vertical distance. |
|
Mt. Washington |
The windiest place on Earth and the location with the worst weather. 1934, highest recorded wind gust (373 hm/h). Average wind speed of 57 km/h. |
|
Wind Energy |
A renewable source of energy that does not emit greenhouse gases. Wild farms are viable in areas with consistent, moderate winds. Issues are noise and vibrations, habitat disruption and Not-in-my-backyardism. |
|
The Prairies and the Far North |
Where wind speed is strongest. |
|
The B.C Interior |
Where wind speed is the lightest. |
|
St.Johns |
The windiest city in Canada. |
|
Windsor |
23rd windiest city. |
|
Eddies |
A disruption in air flow caused by an object. May cause turbulence or wind shear. |
|
Thermal Circulations |
Air flow resulting primarily from the heating and cooling of air. |
|
Breeze |
A wind with a speed of less than 10 km/h. Occur because land needs less heat to warm up than water does. |
|
Sea Breeze |
Occurs in the afternoon, land heats up faster than water; air rises over land, air then flows from water to land. May cause thunderstorms. |
|
Land Breeze |
Occurs during the night, land cools down faster than water, air then flows from the land to the water. |
|
Valley Breeze |
Caused from land warming; the warm air then begins to rise. It exists during the day and the breeze flows up slopes. |
|
Mountain Breeze |
Caused from land cooling; the cool, dense air then begins to sink. It exists at night and the breeze flows down slopes. |
|
Katabatic Wind |
A downslope wind that is stronger than a mountain breeze. Its source regions are often cold and typically flows through narrow canyons and gaps in the mountainside. Found in rugged or isolated areas. |
|
Chinook Wind |
A warm dry wind that rapidly flows down mountainsides and warms as it descends. They are common on the leeward side of high mountain ranges and causes snow to rapidly melt ("snow-eater"). Needs a strong westerly wind aloft and very high mountains to happen. |
|
Desert |
An area that receives less than 250 mm of precipitation annually. |
|
Haboobs |
Formed by downdrafts on the leading edge of a thunderstorm. Also referred to as sandstorms. |
|
Dust Devils |
A small spinning vortex of air formed over hot, dry land. Caused by hot air rising and the wind direction changing due to obstacles. |
|
Monsoons |
Caused by seasonal reversal of wind. Offshore flow during cooler months, onshore flow during warmer months. Orographic lifting leads to extremely high precipitation totals during the onshore flow. |
|
Microscale |
Range of up to a few metres. |
|
Mesoscale |
Range from a few km to hundreds of km. |
|
Macroscale |
Over hundreds of km. Also known as the synoptic scale. |
|
Standard Atmospheric Pressure |
1013.25 mb= 1013.25 hPA= 29.92 in Hg |
|
Clear Air Turbulence (CAT) |
An eddy formed in clean air. |
|
Santa Ana Winds |
A warm, dry wind that blows from the east or northeast into southern California. |
|
Newton’s First Law of Motion |
An object at rest will remain at rest and an object in motion will remain in motion (and travel at constant velocity along a straight line) as long as no force is exerted on the object. |
|
Newton’s Second Law of Motion |
The force exerted on an object equals its mass times the acceleration produced. "F=ma" |
|
Wind Socks |
A form of wind vanes which enable pilots to tell the surface wind direction when landing. |
|
Atmospheric Pressure |
Referred to as barometric pressure. |
|
Barometer |
a device used to measure air pressure |
|
1013 millibars |
Average air pressure at sea level, in millibars |
|
1 bar |
Average air pressure at sea level, in bars |
|
Decreases |
What does air pressure do with altitude? |
|
29.93 inches |
English standard equivalent of 1013millibars/1 bar. |
|
Falling |
Change in pressure that usually indicates increasing cloudiness and precipitation |
|
Rising |
Change in pressure that usually indicates clearing conditions. |
|
Pressure gradient forces |
Three factors that determine wind: _______, coriolis effect, and friction. |
|
Coriolis effect |
Three factors that determine wind: pressure gradient forces, _______, and friction. |
|
Three factors that determine wind |
Pressure gradient, coriolis effect, friction. |
|
Friction |
Three factors that determine wind: pressure gradient forces, coriolis effect, and _______. |
|
Pressure gradient forces |
Force that creates wind. The greater the gradient, the stronger the wind |
|
Coriolis effect |
deflection of winds due to the earth’s spin. |
|
Right |
direction winds are deflected due to coriolis effect in the northern hemisphere |
|
Left |
direction winds are deflected due to coriolis effect in the southern hemisphere. |
|
Stronger |
As wind speed increases, the deflection of wind due to coriolis effect is______. |
|
Equator |
Zone of the earth where deflection of wind due to the coriolis effect is weakest. |
|
Friction |
Factor that affects wind as it moves over different surfaces. |
|
Slows |
Friction _____ wind speed over forested areas compared with open ocean. |
|
Low |
_____ Which air pressure can end up forming cyclones? |
|
Convergence |
When winds come together and are forced to go up, spinning counter clockwise in the northern hemisphere |
|
Cyclone |
weather feature formed by low pressure and air converging and rising, spinning counter clockwise in the northern hemisphere. |
|
High |
_____air pressure can end up forming anticyclones |
|
Divergence |
When air flows down and there is an outflow of air, moving apart in a clockwise direction in the northern hemisphere. |
|
Anticyclone |
weather feature formed by high pressure and air dropping and diverging and spinning clockwise in the northern hemisphere. |
|
Global circulation |
Doldrums at the equator, Horse Latitudes at 30 degrees, |
|
Equatorial low |
Global zone of moist warm air rising at the equator, also called the Doldrums. |
|
Doldrums |
Global zone of moist warm air rising gently at the equator, also called the equatorial low. |
|
Horse latitudes |
Global Zones of dry air descending gently, warmed adiabatically at 30 degrees latitude that creates great deserts, also called the subtropical high. |
|
Trade winds |
Global zones of prevailing winds that blow from east to west from 30 degrees latitude towards the equator in both hemispheres |
|
Westerlies |
Global zones prevailing winds that blow from west to east between 30 degrees & 60 degrees latitude in both hemispheres |
|
Polar high |
Global zones of cool air descending at the poles |
|
Monsoon |
Seasonal change in wind direction where hot land in summer draws air off the sea. |
|
Sea breeze |
Local wind blowing from sea during the afternoon in coastal areas. |
|
Land breeze |
Local wind blowing from land toward water during the night in coastal areas. |
|
Valley breeze |
Local wind blowing from the valley floor up the mountain slopes during the day in mountain valleys. |
|
Mountain breeze |
Local wind blowing from mountain slopes down into the valley in mountain valleys. |
|
Air pressure |
The pressure exerted by the weight of air above. |
|
Barometer |
A device used for measuring air pressure |
|
Pressure gradient |
The spacing of isobars indicates the amount of pressure change occurring over a given distance. |
|
Coriolis Effect |
Wind does not cross the isobars at right angles as you would expect based solely on the pressure gradient. This change in movement results from Earth’s rotation |
|
Jet Streams |
Fast-moving rivers of air that travel between 120-140 kilometers per hour in a west-to-east direction |
|
Cyclones |
centers of low pressure |
|
Anticyclones |
centers of high pressure |
|
Trade winds |
two belts of winds that blow almost constantly from easterly directions. located between the subtropical highs and the equator |
|
Westerlies |
remainder of the air travels toward the poles and is deflected. makes up the dominant west-to-east motion of the atmosphere that characterizes the region son the poleward side of the subtropical highs. |
|
polar easterlies |
winds that blow form the polar high toward the polar low |
|
polar front |
the interaction of warm and cool air masses that produced this stormy belt |
|
monsoons |
seasonal changes in wind directions that are heated and develop low-pressure cells, which permit air to flow onto the land. |
|
prevailing wind |
when the wind consistently blows more often from one direction than from any other |
|
anemometer |
commonly used to measure wind speed |
|
El Nino |
episodes of ocean warming that affect the eastern tropical Pacific. At irregular intervals of three to seven years, these warm countercurrents become unusually strong and replace normally cold offshore waters with warm equatorial waters. |
|
La Nina |
When surface temperatures in the eastern Pacific are colder than average, an event is triggered that has a distinctive set of weather patterns. |
|
sunlight |
What source of energy fuels the wind? |
|
d. air pressure is not associated with weather |
Which of the following statements about air pressure is NOT true? a. air pressure is exerted in all directions b. air pressure equals the weight of air c. air pressure is measured using the element mercury d. air pressure is not associated with weather |
|
a. barometer |
What instrument is used to measure air pressure? a. barometer b. anemometer c. hygrometer d. thermometer |
|
b. wind direction |
Which of the following is influenced by the Coriolis effect? a. wind speed b. wind direction c. air pressure d. pressure gradients |
|
c. pressure gradients |
Which of the following causes wind? a. ocean currents b. land masses c. pressure gradients d. weather patterns |
|
b. clear and fair |
Which of the following best describes weather near the center of a region of high pressure? a. cloudy with rain b. clear and fair c. hurricane d. fog |
|
all directions |
Direction air pressure is exerted |
|
air pressure is decreasing |
Suppose the height of a column in a mercury barometer is decreasing. What is happening? |
|
Sun |
What is the ultimate energy source for most wind? |
|
Coriolis Effect |
What deflects free-moving objects to the right (in the northern hemisphere) or to the left (in the southern hemisphere) |
|
friction is negligble |
Why do jet streams flow parallel to isobars? |
|
isobar |
A line drawn to connect points of equal atmospheric pressure |
|
jet stream |
a high-speed high-altitude airstream blowing from west to east near the top of the troposphere |
|
barometer |
An instrument that measures atmospheric pressure |
|
pressure gradient |
Differences in air pressure |
|
Wind |
Horizontal differences in air pressure. Air flows from areas of higher pressure to areas of lower pressure causes ? |
|
unequal heat of earth’s surface by sun |
What generates air pressure differences (wind)? |
|
pressure differences, Coriolis effect, friction |
What three factors combine to control wind? |
|
steep pressure gradient and high winds |
What does closely spaced isobars on a map indicate? |
|
inward counter-clockwise around low |
Describe how winds blow around pressure centers in the northern hemisphere |
|
Cyclone |
Air pressure decreases toward the center of the cell in __________? Air pressure increases toward the center of the cell in __________? |
|
inward flow around cyclone |
How does friction control the net flow of air around a cyclone and an anticyclone? |
|
heat-transfer system. Warm air from equater toward poles and cold air from poles toward equator |
Describe how the atmosphere balances the unequal heating of earth’s surface |
|
Subpolar low in the southern hemisphere; no landmasses break up the pressure system |
What is the only truly continuous pressure belt? Why is it continuous? |
|
cloud formation and precipitation |
In general, what type of weather can you expect if a low-pressure system is moving into your area? |
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What must happen in the air above for divergence at the surface to be maintained? What type of pressure center accompanies surface divergence? |
Convergence must occur aloft in order for a surface divergence to be maintained. A surface divergence is associated with a high-pressure center |
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cyclone |
(meteorology) rapid inward circulation of air masses about a low-pressure center; the pressure decreases from outer isobars toward the center |
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anticyclone |
(meteorology) winds spiraling outward from a high-pressure center; the values of the isobars increase from the outside toward the center |
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both are zones where two cells, or air masses, converge and air rises, forming zones of low pressure |
Describe the patterns of air circulation at the equatorial and subpolar lows |
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trade winds |
Prevailing winds that blow northeast from 30 degrees north latitude to the equator and that blow southeast from 30 degrees south latitude to the equator |
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westerlies |
Dominant winds of the mid-latitudes. These winds move from the subtropical highs to the subpolar lows from west to east. |
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polar easterlies |
Prevailing winds that blow from east to west between 60degrees-90degrees latitude in both hemisphere. |
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polar front |
the stormy belt where subpolar westerlies and polar easterlies meet |
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topographic effects or variations in surface composition – land and water – in the immediate area |
What causes local winds? |
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away |
Does a sea breeze move toward the sea or away from the sea? |
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the heat differential between land and water increases with the number of hours the sun has been shining |
Why does a sea breeze usually reach its highest speeds in the late afternoon? |
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mountain breeze |
What type of local wind can form in the Grand Canyon at night? |
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direction from which they blow |
How are winds measured? |
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NW |
Toward which direction does a SE wind blow? |
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prevailing wind |
Global winds that blow constantly from the same direction |
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anemometer |
An instrument used to measure wind speed |
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El Nino |
At irregular intervals of 3 to 7 years, these warm countercurrents become unusually strong and replace normally cold offshore waters with warm equatorial waters. |
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El Nino |
An episode – occuring every 3 to 7 years – of ocean warming that affects the eastern tropical Pacific; warm countercurrents become unusually strong and replace normally cold offshore waters with warm equatorial waters. |
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El Nina |
When surface temperatures in the eastern Pacific are colder than average |
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Local Winds |
small-scale winds caused by local variations in air pressure, which are caused by topography and unequal heating of land and water, or unequal heating of air above slopes and valleys |
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West to East |
Describe the general movement of weather in the U.S. |
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Moisture content of air |
What two factors mainly influence global precipitation? |
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a. air pressure |
The force exerted by the air above is called a. air pressure b. convergence c. divergence d. the Coriolis effect |
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c. cyclones |
What are centers of low pressure called? a. air masses b. anticyclones c. cyclones d. jet streams |
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d. wind |
Variations in air pressure from place to place are the principal cause of a. clouds b. lows c. hail d. wind |
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a. high-pressure system |
In the winter, large landmasses often develop a seasonal a. high-pressure system b. low-pressure system c. typhoon d. trade wind |
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a. during mid- to late afternoon |
A sea breeze is most intense a. during mid- to late afternoon b. in the late morning c. late in the evening d. at sunrise |
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a. equatorial low |
What is the pressure zone that is associated with rising air near the equator? a. equatorial low b. equatorial high c. subtropical low d. subtropical high |
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c. jet streams |
What are high-altitude, high-velocity winds? a. cyclonic currents b. isobars c. jet streams d. pressure gradients |
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c. near the poles |
Where is deflection of wind due to the Coriolis effect the strongest? a. near the equator b. in the midlatitudes c. near the poles d. near the westerlies |
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c. polar front |
In what stormy region do the westerlies and polar easterlies converge? a. equatorial low b. subpolar high c. polar front d. subtropical front |
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Strong; Light |
Closely spaced isobars indicate a ______ wind; widely spaced isobars indicate a _____ wind |
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a. converging winds and ascending air – clouds and rain |
Describe the weather that usually accompanies a a. drop in barometric pressure b. rise in barometric pressure |
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deflection to the left |
How does the Coriolic effect modify air movement in the southern hemisphere? |
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equatorial low |
The trade winds originate from which pressure zone? |
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east wind |
On a wind vane with a degree scale, which type of wind is indicated by 90º? |
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1. surface divergence |
1. In the top diagram what type of surface air flow is shown? 2. in the bottom diagram, what type of surface pressure system is illustrated? 3. Select the diagram in which air at the surface first begins to pile up |
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d. subtropical high |
The Sahara in North Africa and the Australian desert, as well as others, are associated with which pressure zone? a. equatorial low b. polar high c. subpolar low d. subtropical high |
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a. high winds |
What does a steep air pressure gradient cause? a. high winds b. light winds c. variable winds d. north winds |
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d. precipitation |
Low-pressure systems are usually associated with a. descending air b. diverging surface winds c. clear weather d. precipitation |
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b. day and flows toward the land |
A sea breeze usually originates during the a. evening and flows toward the land b. day and flows toward the land c. evening and flows toward the water d. day and flows toward the water |
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Air Pressure |
The density or weight of the air |
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Downdraft |
Cold, dense air that sinks |
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Updraft |
Warmer, less dense air that rises |
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Sea Breeze |
On a warm summer day along the coast, as air above land is heated and is replaced by the cooler air from above the surface of the sea. |
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Land Breeze |
Occurs at night when the land cools faster than the sea, the air above the surface water is heated and rises pulling in cooler air from land. |
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Hurricane |
A huge storm that forms over warm ocean water; with strong winds and heavy rains. They are guided by the power of global winds and the gulf stream in the Atlantic Ocean. |
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Tornado |
A destructive, rotating column of air that forms over land and has very high wind speeds and that may be visible as a funnel-shaped cloud |
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high pressure |
A mass of sinking cool air that usually bring fair weather. (sinking air provides stable and sunny weather) |
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low pressure |
A mass of rising warm air that usually bring wet, stormy weather. |
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barometer |
An instrument that measures atmospheric pressure |
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convection current |
The flow that is created due to this heat transfer. As a liquid or gas is heated, it becomes less dense and rises. The cooler liquid or gas (at the surface) is denser and sinks causing a current. |
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wind vane |
Instrument used to measure wind direction |
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water cycle |
The continuous process by which water moves from Earth’s surface to the atmosphere and back. |
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evaporation |
The change of a liquid to a gas |
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precipitation |
Clouds are made up of tiny water droplets that can collide to form larger drops. As the drops grow, they fall to Earth as ___________ |
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Air has lower ___________ the higher the elevation. |
Density |
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elevation |
Height of a landform, such as a mountain, above sea level |
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atmosphere |
Layers of air surrounding the Earth |
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anemometer |
An instrument used to measure wind speed |
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