named after the french scientist gaspard gustave coriolis because of the earth’s rotation, free...
TRANSCRIPT
Named after the French Scientist Gaspard Gustave Coriolis
Because of the Earth’s rotation, free moving objects …• deflected to the right
in the Northern Hemisphere• to the left in the
Southern Hemisphere• Depends on an
object’s speed—higher speed means stronger Coriolis Force.
The Coriolis Force
H
L1007
1009
1011
1013
1015
1017
Pressure (mb)
• A pressure gradient causes wind to blow straight from High P to Low P and accelerate as it goes
North Latitude
Equator
Just a Pressure Gradient
H
L1007
1009
1011
1013
1015
1017
Pressure (mb)
• Wind doesn’t blow straight from High to Low … curves to the right of straight line.
North Latitude
Equator
Pressure, Coriolis Force, Friction
Rotation of Earth
• H and L don’t last forever without energy source … why?
Atmospheric Circulation on Slowly Rotating Earth
Actual flow around pressure systems are never this regular .
Cyclonic Flow Anticyclonic Flow
Curved Flow around High and Low
Around a surface low pressure center, net inward transport of air causes a convergence … air rises in the center.
Cyclones and Anti–Cyclones
Around a surface high pressure center, net outward transport of air causes a divergence … air falls in the center.
Anticyclones : high pressures with nearly circular isobars. • Air descends toward surface due to convergence aloft. • As air nears surface it is forced outward (divergence). • Coriolis effect bends air to the right of its path creating a clockwise rotation.• Under an anticyclone, air is descending, forming an area of higher pressure at the surface.
• Cloud formation is inhibited, so the weather is usually settled with only small amounts of cloud cover.
Anti–Cyclones
Cyclones: Low pressures that exhibit nearly circular isobars. • As air enters low pressure from all directions, Coriolis effect bends wind direction to the right of its path. • This creates counterclockwise rotation around the low and convergence near the center. • As air collides near center it is forced aloft where divergence takes air away from the center.
• Upper-level divergence maintains low pressure. • Rising air cools,condenses helps cloud formation, so weather associated with cyclone is cloudy and wet.
Cyclone
Solid rotation typifies the terrestrial planets: Every part of the object takes exactly the same time to complete one rotation.
Differential rotation typifies Jupiter: Particles at different locations in the fluid take different lengths of time to complete one rotation.