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ATMOSPHERIC CIRCULATION NOTES- AIR/SEA INTERFACE, CORIOLIS, & WIND
OVERVIEW•Atmosphere and ocean one interdependent system•Solar energy creates winds•Winds drive surface ocean currents and waves•Examples of interactions:• El Niño• Currents
AIR/SEA• Ultimately all winds are generated by
unequal heating of the Earth by the sun.• Parallel rays from the sun hit a round
earth, so only at the equator does energy from the sun fall on a flat surface at a right angle to the sun• At the equator, radiation from the sun is
particularly intense, and the air above the tropical oceans warms rapidly each day.• When heated, it expands and becomes
less dense• Results: moist, hot air rises far above the
equator (low pressure)
AIR/SEA• But expanding air cools and cannot retain
moisture…• Instead, water vapor condenses to liquid
water, clouds form, and rains fall in the tropics.• The now dry air move north or south as
strong upper atmospheric winds blow, convecting heat toward the poles
MOVEMENTS IN ATMOSPHERE
• Air (wind) always moves from regions of high pressure to low• Cool dense air, higher surface pressure•Warm less dense air, lower surface pressure
PHYSICAL PROPERTIES OF ATMOSPHERE
•Warm air, less dense (rises)• Cool air, more dense (sinks)•Moist air, less dense (rises)• Dry air, more dense (sinks)
Rises = Low pressure Sinks = High Pressure
AIR MOVEMENT
• Warm air rises• Heat makes molecules move more• Further-apart molecules = lower density• Less dense air rises above more dense air
• Cold air sinks• Colder molecules move less• Become packed more closely together• Denser cool air sinks below less dense air
MOVEMENTS IN AIR ON A ROTATING EARTH
• Coriolis effect causes deflection in moving body• Due to Earth’s rotation to east• Most pronounced on objects that move long
distances across latitudes• Deflection to right in Northern Hemisphere• Deflection to left in Southern Hemisphere• Maximum Coriolis effect at the equator• No Coriolis effect at the poles
THE CORIOLIS EFFECT
• In the Northern Hemisphere:• Objects are deflected to the right• Faster-moving objects are deflected
more• Deflection is stronger closer to the poles
• In the Southern Hemisphere:• Objects are deflected to the left• Faster-moving objects are deflected
more• Deflection is stronger closer to the poles
NORTHERN HEMISPHERE DEFLECTION
N
E
S
W
Equator
Coriolis Effect
NORTHERN HEMISPHERE DEFLECTION
N
E
S
W
Equator
Coriolis Effect
SOUTHERN HEMISPHERE DEFLECTION
N
E
S
W
Equator
Coriolis Effect
SOUTHERN HEMISPHERE DEFLECTION
N
E
S
W
Equator
Coriolis Effect
EXAMPLES:
• A plane leaves Myrtle Beach (South Carolina) for Montreal, but does not correct for the Coriolis Effect. Where does it wind up in relation to its intended destination?
• A plane leaves Myrtle Beach (South Carolina) for San Diego, but does not correct for the Coriolis Effect. Where does it wind up in relation to its intended destination?
Coriolis Effect
San Diego
Aerial Image: NASA
Montreal
Coriolis Effect
San Diego
Aerial Image: NASA
Montreal
Coriolis Effect Not To Scale
Coriolis Effect
Due to coriolis , unequal solar heating, and convection, air patterns actually look like this …sort of
COASTAL WINDS
• Solar heating•Different heat capacities of land and water•Sea breeze • From ocean to land
• Land breeze• From land to ocean
Fig. 6.13
GLOBAL WIND PATTERNS
ATMOSPHERIC CIRCULATION MAP
*Winds - High to Low Pressure*Northern Hemisphere: CounterClockwise; Deflect Right*Southern Hemisphere: Clockwise; Deflect Left
YOUR DIAGRAM