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Definition
above a given point, usually expressed in
millibars (mb) or inches of mercury (in.
Hg) |
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Definition
Mercury barometer
Aneroid barometer |
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Definition
– Column of mercury in a glass tube under vacuum
– Mercury rises or falls with changes in air pressure |
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Definition
Small, sealed chamber partially emptied of air
– Chamber connected to a mechanism that is sensitive
to changes in the chamber
– As air pressure varies, mechanism moves needle on
a dial |
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Definition
the horizontal motion of air
across Earth’s surface |
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Definition
wind updrafts and
downdrafts |
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Definition
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Driving Forces within the
Atmosphere |
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Definition
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Definition
created
because of a pressure difference
between high- and low-pressure
areas |
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Definition
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Definition
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Term
| The closer together the lines |
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Definition
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Term
Because the earth is a sphere and
rotates on its axis,.... |
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Definition
air moving across
the surface appears to curve. |
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Term
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Definition
Apparent deflection of
straight line to the right in
the Northern Hemisphere
and to the left in Southern
Hemisphere |
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Term
The effects of wind friction near the surface
extends to a height of about |
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Definition
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Term
| Variables affecting friction: |
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Definition
– Surface texture
– Wind speed
– Time of day and year
– Atmospheric conditions |
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Term
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Definition
friction disrupts equilibrium
between pressure gradient and Coriolis forces: |
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Term
Near the surface, friction disrupts equilibrium
between pressure gradient and Coriolis forces: |
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Definition
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Term
| Primary high- and low-pressure areas: |
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Definition
– Interrupted cells or uneven belts of similar pressure
that stretch across the globe |
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Term
Secondary high- and low-pressure areas are
smaller than the primary systems |
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Definition
– Form within the primary pressure areas
– Range from a few hundred to a few thousand
kilometers in diameter
– Hundreds to thousands of meters high |
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Term
Primary High-Pressure and Low-
Pressure Areas |
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Definition
| Equatorial low-pressure trough |
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Term
Rising warm air
creates an
equatorial trough,
low- pressure belt
called the |
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Definition
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Term
Rising warm air
occurs within the |
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Definition
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Term
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Definition
| Here, trade winds converge near equator |
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Definition
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Definition
Monotony of the weather has given rise to the
expression |
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Term
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Definition
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Term
In northern hemisphere, trade winds blow
mainly towards the |
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Definition
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Term
In northern hemisphere, trade winds blow
mainly towards the southwest: |
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Definition
Utilized by mariners for trade when traveling
from Europe to America
– Caused Columbus to land in West Indies
rather than continental North America |
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Term
Trade winds in the southern hemisphere
are important in affecting _____ |
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Definition
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Term
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Definition
south-easterly winds
blowing towards the northwest diminish |
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Definition
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Rising air within ____ once aloft,
moves towards the poles |
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Definition
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Term
This northward-moving air, however,
must converge aloft cause... |
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Definition
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Term
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Definition
energy into
outer space, cools, and becomes
more dense, causing it to sink in
regions known as highs. |
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Term
....masses aloft causes
the air to sink at
~30o north and
south latitudes to
form Subtropical
Highs |
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Definition
| convergence and cooling of air |
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Term
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Definition
| Occur close to 30o north and south latitudes |
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Term
| Downwelling air is dry (why?): |
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Definition
| Worlds largest deserts occur in these zones |
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Term
| subtropical highs (gentle winds) |
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Definition
Ships sailing to America often languished in
these regions due to lack of winds |
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Term
| When food supplies diminished.... |
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Definition
horses were
either eaten or thrown overboard to lighten
load
– Hence the term “horse latitudes” |
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Term
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Definition
higher latitudes than
the trade winds |
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Term
In northern hemisphere, westerlies mainly
blow from the... |
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Definition
| west towards the northeast |
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Term
In northern hemisphere, westerlies mainly
blow from the west towards the northeast: |
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Definition
– Utilized by sailors returning to Europe from
North America |
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Term
| The Bermuda High steers the paths of |
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Definition
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Term
In winter, two cells dominate around 60o N
latitude but weaken or disappear in summer: |
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Definition
Aleutian low in the Pacific Ocean
– Icelandic low in the Atlantic Ocean |
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Term
| Polar atmospheric mass is |
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Definition
small and receives
little energy from the sun |
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Term
| Cold air aloft sinks towards the surface |
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Definition
– Descending winds diverge clockwise near the surface
in N. hemisphere (counterclockwise in S.
hemisphere)
– Surface winds moving away from northern polar
region are therefore anticyclonic |
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Term
Arctic high less pronounced than Antarctic
high: |
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Definition
– Arctic high tends to form over continental areas in
winter (Canadian and Siberian highs) |
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