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The Coriolis Force. 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
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The Coriolis Force Named after the French Scientist GaspardGustaveCoriolis • Because of the Earth’s rotation, free moving objects … • deflected to the right in the Northern Hemisphere • to the left in the SouthernHemisphere • Dependson an object’s speed—higher speed means stronger Coriolis Force.
Just a Pressure Gradient H Pressure (mb) North Latitude 1017 1015 • Apressure gradientcauseswind to blow straight fromHigh P to Low P and accelerate as it goes 1013 1011 1009 Equator 1007 L
Pressure, Coriolis Force, Friction H Pressure (mb) North Latitude 1017 • Wind doesn’t blow straight from High to Low … curves to the right of straight line. 1015 1013 1011 • H and L don’t last forever without energy source … why? 1009 Equator 1007 L Rotation of Earth
Curved Flow around High and Low Cyclonic Flow Anticyclonic Flow Actual flow around pressure systems are never this regular .
Cyclones and Anti–Cyclones Around a surface low pressure center, net inward transport of air causes a convergence … air rises in the center. Around a surface high pressure center, net outward transportof air causes a divergence … air falls in the center.
Anti–Cyclones • Anticyclones: high pressures with nearly circular isobars. • Air descends toward surface due to convergence aloft. • As air nears surface it is forced outward (divergence). • Corioliseffect 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.
Cyclone • Cyclones: Low pressures that exhibit nearly circular isobars. • As air enters low pressure from all directions, Corioliseffect 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 cycloneis cloudy and wet.
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.