ESC 1000
Chapter 18 Vocabulary
1. air
pressure - the
force exerted by the weight of a column of air above a given point.
2. aneroid
barometer - an
instrument for measuring air pressure that consists of evacuated metal chambers
very sensitive to variations in air pressure.
3. anticyclone - a high pressure center
characterized by a clockwise flow of air in the northern hemisphere
4. barograph - a recording barometer.
5. barometric
tendency - the
nature of the change in atmospheric pressure over the past several hours. It
can be a useful aid in short range weather prediction.
6. chinook - a wind blowing down the leeward
side of a mountain and warming by compression.
7. convergence
- the condition that exists when the distribution of winds within a
given area results in a net horizontal
inflow of air into the area. Because this at lower levels is associated with an
upward movement of air into the areas of these winds are regions favorable to
cloud formation and precipitation.
8. Coriolis
effect - the
deflective force of earths rotation on all free moving objects, including the
atmosphere and oceans. Deflection is to
the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
9. Country
breeze – A
circulation pattern characterized by a light wind blowing into a city from the
surrounding countryside. It is best developed on clear otherwise calm nights
when the urban heat island is most pronounced.
10. cup
anemometer - an
instrument used to determine wind speed.
11. cyclone - a low pressure center
characterized by a counter clockwise flow of air in the northern hemisphere.
12. divergence - the condition that exists when
the distribution of winds within a given area results in a net horizontal
outflow of air from the region. In these at lower levels the resulting deficit
is compensated for by a downward movement of air from aloft; hence, areas of
these winds are unfavorable to cloud formation and precipitation.
13. El Niño - the name given to the periodic
warming of the ocean that occurs in the central and eastern Pacific. One of
these major episodes can cause extreme weather in many parts of the world.
14. equatorial
low - a belt of low
pressure lying near the equator and between the subtropical layers.
15. geostrophic
wind - a wind
usually above a height of 600 meters that blows parallel to the isobars.
16. high - a
center of high pressure characterized by anticyclonic winds
17. isobar - a line drawn on a map connecting points of equal
atmospheric pressure, usually corrected to the sea level.
18. jet
stream - swift
(120-240) kilometers per hour) high altitude winds.
19. land
breeze - a local
wind blowing from land toward the water during
the night in coastal areas.
20. La Niña - an episode of strong trade winds
unusually low sea surface temperatures in the central and eastern pacific. The
opposite of El Niño.
21. low - a center of low pressure
characterized by cyclonic winds.
22. mercury barometer - a mercury filled glass tube in
which the height of the mercury column is a measure of air pressure.
23. 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.
24. mountain breeze - the nightly downslope winds
commonly encountered in mountain valleys.
25. polar easterlies - In the global pattern of prevailing
winds. winds that blow from the polar high toward the subpolar low. These winds, however should not be thought of
as persistent winds such as the trade winds.
26. polar
front - the stormy
frontal zone separating air masses of polar origin from air masses of polar
origin from air masses.
27. polar
high - anticyclones
that are assumed to occupy the inner polar regions and are believed to be
thermally induced at least in part.
28. pressure
gradient - the
amount of pressure change occurring over a given distance.
29. pressure
tendency - the
nature of the change in atmospheric pressure over the past several hours. It
can be a useful aid in short range weather prediction.
30. prevailing
wind - a wind that
consistently blows from one direction more than from another.
31. Santa Ana - the local name given a chinook wind
in southern California.
32. sea
breeze - a local
wind blowing from the sea during the afternoon in coastal areas.
33. Southern Oscillation - the seesaw pattern of atmospheric
pressure between the eastern and western
pacific.
34. subpolar
low - low pressure
located at about the latitudes of the Arctic
and Antarctic circles.
35. subtropical
high - not a
continuous belt of high pressure but rather several semipermanent, anticyclonic
centers characterized by subsidence and divergence located roughly between latitudes
25 and 35 degrees.
36. trade
winds - two belts
of winds that blow almost constantly from
easterly directions and are located on the equatorward sides of the subtropical
highs.
37. valley
breeze - the daily
upslope winds commonly encountered in a mountain valley.
38. westerlies - the dominant west to east motion
of the atmosphere that characterizes the regions on the pole ward side of the
subtropical highs.
39. wind - air flowing horizontally with
respect to earth's surface.
40. wind vane - an instrument used to determine
wind direction.