2 Balance of forces in the fluid motion Forces due to planetary rotationCentrifugal force GeoidCoriolis force Deflection of moving fluidPressure gradient forceFrom high to low pressure
3 _ + Deflection of air flow due to Coriolis force Low Pressure Surfaces ofconstant pressurey (latitude)x (longitude)+High Pressure
4 Balanced flow: geostrophic balance FpressureLow PressureHigh PressureFCoriolisCoriolis force 90 degrees to the rightPressure force down the gradientAir flows along the line of constant pressureParticles will have the high pressure on their right (opposite in the southern hemisphere)
5 Geostrophic circulation What would be the direction of (1) the pressure force and (2) the Coriolis force in geostrophic balance?What would be the direction of geostrophic flow?LHCyclonicAnti-cyclonic
6 Geostrophic circulation Now we are in the Southern Hemisphere, what would be the direction of the geostrophic flow?LHCyclonicAnti-cyclonic
7 H H L H H Tropical cyclone: an intense low pressure system Air circulates around the low pressure
8 Flow under radial pressure gradient A bucket full of waterOpen up a hole in the middleGenerates a low pressureWhat would happen to the water?Non-rotatingRotating
9 Tropical cyclones Coriolis effect Air flows around the low pressure counter-clockwiseEnergy sourceWarm, moist air from tropical ocean
11 Storm surge Graphic illustration by National Hurricane Center
12 Atmosphere-ocean interaction What are the ways that the Earth’s atmosphere and ocean interact?
13 Wind-driven ocean currents Atmospheric winds applies frictional force on the surface waters Ocean wavesWind-driven circulation(next week)
14 Water cycleImplications to the salinity of seawater?
15 Temperature ITCZ Salinity Subtropics Warm SST, low SSS Excess precipitationSalinitySubtropicsWarm SST, high SSSExcess evaporationSea surface temperature and salinity are controlled by air-sea interaction