Chapter 18 air pressure and wind
What is a breeze? Breeze named based on ______________ blow from _________ to __________ pressure.
a light wind where they originate high, low
Closely spaced isobars indicate______ and ________. Widely space isobars indicate _________ and _________.
a steep pressure gradient , strong winds a weak pressure gradient and light winds.
How would air flow if Earth did not rotate?
air would move directly from high to low pressure If the Earth did not rotate, air would move directly from high pressure (the poles)to low pressure(the equator) because of the pressure gradient force. The direction of the wind deviates because of the Coriolis effect. The deviation (deflection) is caused by the rotation of the Earth.
Fair weather can usually be expected with the approach of a(n) _________. cold front anticyclone cyclone low-pressure system
anticyclone
What is the technical name for a high-pressure center?
anticyclone
mountain breeze
breeze from the mountain( high) into the valley( low) night the mountain cools down faster than the valley ↓ the air form cold and dense ↓ creates High pressure the valley the air is warm and less dense ↓creates Low pressure The nightly downslope winds commonly encountered in mountain valleys.
In the Northern Hemisphere, which way do winds associated with a high-pressure system blow?
clockwise and toward the center.
What is a polar high pressure zone?
cold, subsiding air sinks= create high pressure at 90 degrees. Air spreads towards the equator. Anticyclones that are assumed to occupy the inner polar regions and are believed to be thermally induce(give rise to), at least in part.
sea breeze
comes from the ocean onto the land daylight the land heats up faster than the ocean ↓ forms warm air and it is less dense, rise up ↓creates Low pressure the ocean is cool air ↓ dense and creates High pressure Wind flows from H to L pressure.
Wind speed is usually measured using what
cup anemometer ( anemos= wind in Greek)
Air pressure (increases/decreases) with increasing altitude?
decreases, it gets harder to breathe
Two basic measurements of wind
direction and speed
winter monsoons bring (over continents)
dry air and moderate temperatures the ocean is warm quicker than the land Ocean -Low pressure Land- High pressure Land Wind blows H to L- forced upward. Oceanside- Air rise up- cool-reaches saturation- forms cloud and precipitation. dry continental air flow off the land
Who first noticed a pattern(El Nino) that water temp was warmer than normal?
fisherman from Ecuador and Peru
valley breeze
flows from the valley up the mountain daylight mountain(heats up faster than the valley)= unequal heating. the air on the mountain warm and less dense ↓ creates low pressure valley the air above the valley cold and dense ↓ creates High pressure The wind blows from H to L pressure The daily upslope winds commonly encountered in a mountain valley
Surface winds blow across(cut) the isobars at an angle due to:
friction,pressure gradient,Coriolis effect
How does wind flow?
from out of area of high pressure into area of low pressure
What do seasonal temperature differences disrupt Which hemisphere is most obvious influence
global pressure patterns & wind patterns Northern
The values of the isobars of a high-pressure system _________ from the outer areas toward the center of the high. stay the same increase decrease are strongest None of the choices are correct.
increase
The effect of friction on wind
is only important near the earth's surface. acts to slow the air's movement.
What does friction impact Coriolis effect ?
it makes Coriolis effect lessen. why? slower winds deflect less than winds travel at faster speeds.
jet stream
like a river of air in the atmosphere, where air currents(流れ) travel at high speed=high velocity (70-140) mph High altitude curents=Near the top of the troposphere
The largest number of cyclones are generated during __________. months with the greatest temperature gradients December months with the lowest temperature gradients July None of the choices are correct.
months with the greatest temperature gradients
land breeze-1
movement of air from land to sea at night, created when cooler, denser air from the land forces up warmer air over the sea
Upper air winds are __________
no friction because friction is only near the surface.
Steady pressures mean ________ are occurring, and the weather typically remains ___________.
no pressure changes,the same
Winds are labeled from where they
originate (e.g, North wind-blows from the North toward the south)
Upper level winds are___________ to Isobar Upper level winds are moving________ because there is ___________. Upper level winds predict us ________________.
parallel faster, no friction air direction
What kind of zone does the air spread towards the equator?
polar high pressure zone
pressure gradient
pressure change over distance air pressure difference the two locations. For example, the North Pole and the warmer equatorial region.
What are the three factors that control wind?
pressure gradient-the most important factor affects both wind and direction. Coriolis effect- mainly affects wind direction hon wind is moving.-curving and bending. Friction-affect mainly winds speed because it is near the surface.
All local wind are set up by ____________________
pressure gradients( caused by temp different) Any localize wind are caused by pressure gradient.
A steep pressure gradient ________. A steep pressure gradient is associated with what type of pressure system?
produces strong winds Low
Equatorial low pressure zone
raising air & abundant precipitation Rainy & stormy places because of moist, warm air.
Cyclone's air (rises/sinks)?
rises inward ( convergence= rising up)
Anticyclones air (rises/sinks)?
sinks outward (divergencen=spread out at the surface)
The surface wind is always ___________ than upper wind because of __________.
slower, friction.
_________________ is the ultimate energy source for most wind.
solar radiation
What do closely spaced isobars indicate?
steep pressure gradient and strong winds(high wind or subsequent high winds) The spacing of the isobars indicates the amount of pressure change occurring over a given distance and is called the pressure gradient force. A steep pressure gradient will cause greater acceleration of a parcel of air than a weak pressure gradient will.
What do closely spaced isobars indicate? What do widely spaced isobars indicate?
strong pressure and strong winds wind speed is faster around low pressure. the more closer the isobars, the faster the wind is
What kind of pressure zone are polar fronts?
subpolar low pressure zone
What is a subtropical high pressure zone?
subsiding, stable, dry air at 30 degrees latitude The majority of the world's deserts are found here. example Sahara, Africa- the largest desert on the earth. High pressure gives us nice dry clear day condition.
What kind of pressure zone are the majority of deserts?
subtropical high pressure zone
Local winds are produced from
temperature differences small-scale winds A small-scale wind produced by a locally generated pressure gradient. Examples include land and sea breezes and mountain and valley breezes.
Where is jet stream formed ?
the boundary between hot and cold air masses.
land breeze
the breeze from the land (high)to the Ocean(low) night Land cools faster than the Ocean ↓ cool dense air forms high pressure the air above the ocean is warm ↓ less dense ↓creates low pressure The breeze flows from High to Low.
Coriolis Effect
the curving of the wind due to the Earth spinning, deflection is to the right in the NH and to the left in the SH. causing the moving wind to deflect from their original path due to the rotation of the earth The Coriolis force is the deviation in the direction of all free-moving objects or fluids, which is caused by the rotation of the Earth. In the Northern Hemisphere the deviation is to the right of the path of motion, and in the Southern Hemisphere the deviation is to the left of the path of motion.
El Nino now refers to________________ of the normal currents(Pattern) in where_________.
the large scale reversal, the Pacific Ocean
Coriolis effect is strongest at_________ and weakens ______________
the poles equator ward, becoming nonexistent at the equator.
El Nino was named from
the warm-countercurrent( counter=opposite, current= movement of air)that flows south along the coasts of Ecuador and Peru.
Why are jet streams important?
they play an essential role in the global transfer of heat from the equator to the poles. important because they affect our weather= determine the track of storms.
What is a barograph?
type of aneroid that continuously measures the air pressure, draws the air pressure on a chart A recording barometer.
What causes local winds?
unequal heating of Earth's surface within a small area Small-scale winds produced by a locally generated pressure gradient are known as local winds. The local winds are caused either by topographic effects or by variations in surface composition--land and water--in the immediate area.
What does El Nino block ?
upwelling of colder, nutrient-filled water. A huge upwelling regular occurs off the coast of Peru-which enjoys a large fishing industry as a result. Upwelling is a result of winds and the rotation of the Earth.
What is a subpolar low pressure zone?
warm & cool winds(current) interact(collied) at 60 degrees polar front- an area of storms one of the stormiest and snowiest regions on the earth. Example: Northern Canada, Siberian North Russia
What is El Nino?
warmer than average water (temp) in the pacific ocean off South America
Upper-level winds in the middle latitudes of both hemispheres generally blow from ____.
west to East
The general movement of low-pressure centers across the United States is from ___________. east to west northeast to southwest west to east north to south south to north
west to east
What is the horizontal movement of air called? Air flowing horizontally with respect to Earth's surface.
wind
Instrument for measuring wind direction is
wind vane ( weather vane) little arrow spinning around
When are upper air winds fastest?
winter The steep temperature gradient across the middle latitudes in the winter months corresponds to a stronger flow aloft (faster wind speeds). In the winter when the temp differences between warm and cold are more dramatic. So, Jet streams can go much faster(250 miles per hour or more)
What is an isobar? What are its units?
(iso= equal, bar= pressure) lines of equal air pressure in the atmosphere. millibars
Why do we still use mercury even if it is very toxic ?
1.It is very dense(heavy) and won't evaporate like other liquids. Most liquids tend to evaporate. 2.accuracy= easy to read and define line(sharp line). As on water, it would evaporate, water droplets around a glass tube. 3. maintenance free- nothing is wrong.
What is the standard sea level air pressure?
1013 millibars, 29.92 inches of mercury
What is standard sea-level pressure in millibars, in inches of mercury, and in pounds per square inch ?
1013 millibars, 29.92 inches of mercury,14.7 pounds per square inch
What is the weight of the air at sea level?
14.7 pounds per square inch PSI is great for cars' tires or bicycles tire but doesn't work for the atmosphere because it is small enough. Sea level= common starts elevation level around the world.
at what interval are isobars drawn on this map? That is, what the difference, in millibars, between each succeeding isobar?
4 mb
Which of the following describes the subpolar low (polar front)?
A zone where the polar easterlies and the westerlies converge As the prevailing westerlies move toward the poles, they converge with the cool polar easterlies in the region of the subpolar low. The interaction of these warm and cool winds produces the stormy belt known as the polar front. The source region for the variable polar easterlies is the polar high. In that zone, cold polar air subsides and spreads toward the equator. Rising air is associated with the pressure zone known as the equatorial low, which has ascending hot, moist air that is marked by abundant precipitation.
geostrophic winds
Airflow that moves parallel to the isobars (west to east) because they are resulting from the Coriolis force and the pressure gradient force are combined and are equal to each other A wind, usually above a height of 600 meters (2000 feet), that blows parallel to the isobars.
Which of the following is/are associated with high air pressure systems? Clear weather Descending air Diverging winds All of the answers are correct.
All of the answers are correct.
Global distribution of precipitation is closely related to _________. latitude topography distribution of land and water global patterns of air pressure and wind patterns All of the choices are correct.
All of the choices are correct.
Which of the following factors contribute(s) to our wind patterns? Solar radiation Pressure gradient Coriolis force Friction All of the choices are correct.
All of the choices are correct.
Which of these factors influence(s) the magnitude of the Coriolis force?
Both wind speed and latitude Both wind speed and latitude influence the magnitude of the Coriolis force. In addition, the Coriolis effect is strongest at the poles and weakens toward the equator. At the equator, the Coriolis effect is nonexistent.
El Nino appeared in Ecuador and Peru during what time of year
Christmas/Winter
Monsoons occur over_________during_____________.
Continents, warm months ( in summer) Land heats up quicker than the ocean. Land- warm air became denser-create-low pressure above the ocean is cooler and denser-create High pressure wind blow H to L- it rises- the air cool-reaches saturation-form cloud- precipitation.
Episodes of ocean warming that affect the eastern tropical Pacific are called ____________. La Niña El Niño trade winds monsoons None of the choices are correct.
El Niño
atmospheric pressure
Forced exerted (caused) by the weight of the air above
What are lines on a weather map connecting places of equal air pressure called?
Isobars
What are fast-moving currents of air found near the top of the troposphere?
Jet Streams
High-altitude, high-velocity "rivers" of air are referred to as what?
Jet streams
___________tend to be westerly, which means they blow from the west to the east.
Jet streams
Which of the following is not a likely possible condition during an El Niño event? More hurricane damage from the Atlantic Warmer temperatures west of the Rockies Drought in Australia Warmer ocean water near the Galapagos Islands Trade winds weaken
More hurricane damage from the Atlantic
An anticyclone spins what direction in the Northern Hemisphere/Southern Hemisphere?
NH- clockwise, SH- counterclockwise (H on a weather map)
A cyclone spins what direction in the Northern Hemisphere/Southern Hemisphere?
NH- counterclockwise, SH- clockwise
Which of the following respond(s) to the Coriolis effect?
Only wind direction
What are the advantages to use the Aneroid barometer ?
Portable, continuous reading. Altimeter - measures altitude using air pressure.
Which of the following is/are usually associated with low air pressure systems? Descending air Precipitation Diverging winds Clear weather
Precipitation
What is the most important factor to control wind ( the movement of air)?
Pressure gradient If it doesn't have different pressure, the atmosphere doesn't move.(air won't move if the pressure gradient doesn't exist)
Which of the following factors are responsible for producing wind?
Pressure gradient and solar radiation
What is the name of the force that causes wind to blow?
Pressure gradient force The pressure gradient force causes wind to blow. The force that generates wind results from horizontal pressure differences. When air is subjected to greater pressure on one side than on the other, the imbalance produces a force that is directed from the region of higher pressure toward the region of lower pressure. The greater these differences, the greater the wind speed.
Monsoon
Seasonal change in wind direction ( moisture pattern) Seasonal winds bring a change in weather. Seasonal reversal of wind direction associated with large continents, especially Asia. In winter, the wind blows from land to sea; in summer, from sea to land.
Millibar at standard sea lever pressure is 1013mb. 960-1040 mb ranges Standard sea level (1013 mb) compare to the range(940-1040 mb) it is below and above 40 mb-4% What does 4/% change mean to atmosphere ?
Small changes air pressure like 4% is significant change for atmosphere.
How would the air pressure change if "fair" weather were approaching? The air pressure would fall. The air pressure would remain steady. The air pressure would rise.
The air pressure would rise. Fairweather can usually be expected with the approach of a high-pressure center (rising) because descending air is compressed and warmed. This results in cloud formation and precipitation being unlikely in an anticyclone.
What is the pressure gradient force (PGF)?
The force of pressure from high to low air pressure
Who invented the mercury barometer?
Torricelli in 1643
What is an aneroid barometer?
a barometer that doesn't have liquid and uses an expanding chamber. aneroid means without liquid An instrument for measuring air pressure that consists of evacuated metal chambers that are very sensitive to variations in air pressure.
What is a mercury barometer?
a barometer that measures the air pressure from a vacuum and mercury in a glass tube.
What is a cyclone?
a center of low-pressure, pressure decreases towards the center (L on a weather map) A low-pressure center is generally related to unstable conditions and stormy weather. The rising air associated with a low-pressure center often results in cloud formation and precipitation.
Friction
a force that restricts motion anytime an object comes in contact with a surface- it experience friction- the rougher the surface, the more friction it will experience. For example, sandy dessert, wind move over it easily. a rough mountain range is likely slow
