Meteorology Test 2 Objectives (Ch. 18 & 19)
No description yet. This curated deck is ready for daily study.
Card preview (24)
Describe, in general, how a mercury barometer and an aneroid barometer measure air pressure.
mercury barometer - a tube with one closed end filled with mercury inverted into a dish of mercury. The mercury flows out of the tube until the weight of the column was balanced by the pressure that the atmosphere exerted on the surface of the mercury in the dish. When air pressure increases, the mercury in the tube rises; when it decreases, so does the mercury. aneroid barometer - uses a partially evacuated metal chamber which is extremely sensitive to variations in air pressure. It changes shape, compressing as the pressure increases and expanding as the pressure decreases. A series of levers transmit the movements of the chamber to a pointer on a dial that is calibrated to read in inches of mercury and/or millibars.
State normal sea level atmospheric pressure in lbs/in2, inches of mercury, and millibars.
(14. 7 lbs/in2) 29. 92 inches of mercury 1013. 2 millibars
What do isobars represent on a weather map and how can they be used to locate high or low pressure regions and areas of high or low wind speed.
Isobars are lines connecting points of equal pressure. (Differences in pressure create wind. The pressure gradient force drives the winds from higher pressure to lower pressure.) Closely spaced isobars - steep pressure gradient - air pressure changes rapidly - high winds Widely spaced isobars - weak pressure gradient - air pressure changes gradually - light winds
Interpret wind speed and direction symbols.
The end of the line with the barbs is the end pointing where the winds come from; wind direction is always recorded as where it is coming from NOT where it is going to. half barb = 5 knots full barb = 10 knots flag = 50 knots
What is the cause and effect of the Coriolis force?
The cause is the Earth’s rotation. The wind is deflected to the right of its path of motion in the Northern Hemisphere and to the left in the Southern Hemisphere.
How does the wind move relative to isobars near the surface and at higher altitudes (geostrophic winds)?
At the surface (below 600 meters/2000 feet), wind move at an angle across the isobars, toward the area of lower pressure (want to go straight, but Coriolis effect deflects it). At higher altitudes, wind moves parallel to the isobars.
Given a set of isobars and their pressures, identify an area as a high or low, give its meteorological name, describe its surface air circulation patterns, describe the most likely sky conditions, and describe the air currents (vertical air movement) near its center.
/
Name, locate, and describe the dominant high and low pressure areas of the Earth.
Doldrums: low pressure belt around equator; winds light and variable, often calm; lots of rain; ITCZ (Intertropical Convergence Zone) Horse Latitudes: about 30 degress latitude; air is descending (High pressure), little surface wind; dry (great deserts of the world are located here) Subpolar Low/Polar Front: warm air from south meets cold air from the north; produces stormy belt-lowpressure Polar High: a high pressure over the poles -a cold desert
Name, locate, and describe the general atmospheric wind patterns of the Earth.
Trade Winds: (NE in North Hemisphere, SE in the Southern) light and steady Westerlies: come from west; 40 degress latitude; in South, over large stretches of ocean; US in this area Polar Easterlies: come from east
Describe the polar jet stream and its approximate location. Why is it important in describing and predicting the weather?
a rapidly moving river of air; can have wind speeds greater than 100 mph; winter: 4-6 miles altitude, about 30 deg latitude; summer: >6 miles altitude, about 50 deg latitude. It tends to guide low-pressure centers (storms) across North America. Flows west to east. Southern states get more of their stormy weather during winter. During summer, when jet stream is further north, the West Coast has an extended dry season. Cooler air is located to the North of the jet, warmer air to the South of the jet.
Compare and contrast the wind, pressures, and weather along the equatorial Pacific under La Nina and El Nino conditions.
El Nino: Strong equatorial countercurrents(move to east) amass large quantities of warm water that block the upwelling of colder, nutrient-filled water along the west coast of South America. Causes more rain in normally arid regions and lowers pressure in western Americas. Weak trade winds. Weak Peru Current. Pressure increases and dryer than normal in western Pacific (Australia). La Nina: Strong equatorial currents (move west) bring warm water to western Pacific, wetter than normal Australia, low pressure; strong trade winds; high pressure and cool water in western Americas; strong Peru Current; dryer than normal; colder northwestern US
To what does the Southern Oscillation refer?
the seesaw pattern of atmospheric pressure between the eastern and western Pacific. Each time an El Nino occurs, the barometric pressure drops over large portions of eastern Pacific and rises in western Pacific; as El Nino comes to an end, the pressure difference between those two regions swings back in the opposite direction, triggering a La Nina event.
Describe the cause and effect of monsoons, sea and land breezes, and mountain and valley breezes.
monsoon: 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. In coastal areas during warm summer months, the land is heated more intensely during the daylight hours than is the adjacent body of water. sea breezes: a noon/afternoon breeze which develops as the cooler air over the water (higher pressure) moves toward the warmer land (lower pressure) land breezes: at night, reverse of sea breeze may take place; land cools more rapidly than sea, so land breeze develops mountain breezes: at night, air above mountain slopes cools rapidly and drains into warm valley valley breezes: during the day, air above mountain slopes is heated and rises
What are chinook winds? (textbook question)
a wind blowing down the leeward side of a mountain and warming by compression
How is an air mass classified? Name the air masses that affect Arkansas’s weather most. What, in general, will the weather be like with the air masses that affect the U.S.?
Classified by where they originate - their source region. cP; mT mT - high temperatures, oppressive humidity, precipitation in summer cP - in winter, brings clear skies and cold temps; early winter lake effect snows; in summer, it can bring a few days of cooler temps mP - source of moisture for winter heavy rain and snow in western US; can produce a winter nor’easter in New England
When and how are “lake effect” snows produced?
Snow showers associated with a cP air mass to which moisture and heat are added from below as the air mass traverses a large and relatively warm lake (such as one of the Great Lakes), rendering the air mass humid and unstable.
What, in general, is a front? Draw and/or recognize weather map symbols for a: • cold front • warm front • stationary front • occluded front
A front is the boundary between two air masses. cold front - triangles warm front - semicircles stationary front - triangles and semicircles on opp. sides occluded front - triangles and semicircles alternating on one side of line
Describe a warm front or a cold front with the aid of a cross-sectional diagram of the front. Include: • the location of cold and warm air, the slope, and speed of the front • the location and type of clouds, and characterize any precipitation
see second page of Ch. 19 notes cold: slope 1:100 avg. speed 20-25 mph warm: slope 1:200 avg. speed 10-15 mph
Describe the atmospheric conditions and weather associated with the passage of a mid-latitude cyclone. Include: • types of air masses • types of clouds expected and where • barometric tendency • areas of precipitation • wind directions • temperature and humidity changes
air masses: cP, mT, mP pg. 584-585, especially bullets on 585
As it relates to the global circulation patterns, where do most mid-latitude cyclones form?
Polar Front (Subpolar Low)
What is necessary at higher altitudes in order for a low to persist?
Surface convergence must be matched by divergence aloft.
How is a hailstone formed?
successive freezing of layers of water
Give a general description of a thunderstorm and describe the two common situations they form in.
A thunderstorm is any storm that produces lightning and thunder; occur in a cumulonimbus cloud; small scale, short-lived systems; produce strong updrafts, gusty surface winds, heavy rain Air Mass Thunderstorms - occur in mT air masses; scattered; most common in tropics; in US most common in summer in late afternoon and early evening; tend NOT to produce severe weather Frontal Thunderstorms - occur along fronts, especially along cold fronts; may occur in clusters rather than as isolated storms; can produce severe weather- high winds, hail, flooding, tornadoes
What role does latent heat play in the development of a thunderstorm?
All thunderstorms require warm, moist air, which, when lifted, releases sufficient latent heat to provide the buoyancy necessary to maintain its upward flight.