EPS 102 lecture 16

EPS 102 lecture 16 - EPS 102 lecture 16 Tuesday March 16th...

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EPS 102 lecture 16 Tuesday March 16 th , 2009 Coriolis Force: relates to motions in the atmosphere. Rotation provides the kind of flows that are really good at reproducing and regenerating magnetic fields. The same dynamic applies to the oceans and ocean currents. The oceans are more difficult because we don’t have the information: we do not live inside of them, but satellite observations make up for it. The solid earth also plays a role in the atmosphere that then couples to the ocean. Connecting all of these things is the Coriolis Force. Greenhouse Effect and solar radiation that comes into Earth and warms up the planet. 1370 watts/m^2 is the amount of energy that comes in per square meter. To get the average surface temperature, we took the average : 1370 and distributed it uniformly over Earth = 325 watts/m^2 and some of this gets reflected back so 235 actually gets absorbed. How in detail does the solar radiation come in on the surface of the earth? If you put a hula hoop on the equator, you would get close to 1370 watts/m^2 on the equator. If you go to the North pole and put the hula hoop there, it is not pointing perpendicular to the sun and pointing it obliquely and you are spreading all that energy over a larger area, so it is less than 1370 watts/m^2. We are getting a lot of solar radiation at the equator and little at the poles but we average it out to get 325. The atmosphere takes excess energy and redistributes it to places which are below average so we get a little more uniformly distributed temperature. We warm up air at the equator and transfer it to the poles. If our planet wasn’t rotating and just fixed in space, we might expect: heating up the ground, rising up towards where it was cold and then set up a circulation pattern = convective pattern. But due to our earth’s rotation, we deviate from this model. Venus has a funny slow rotation rate, and it rotates in the opposite direction of Earth. On Venus we tend to get winds in the equatorial region, but Coriolis on Venus is less important on atmospheric motion than on Earth. Since we have rotation on Earth, an observer at different latitudes has different velocities. Someone on the pole would only be turning around like a merry go round going nowhere. The person on the equator has a higher velocity=650 km/hr. Force=ma in an inertial reference frame. The direction of motion wouldn’t be the same because at different sides of the planet people are going into and out of space. This is an accelerated frame. Imagine you have a “merry go round” at the pole, and their velocity = 0. But if they throw a ball and no force acts on it, then the ball will go straight. But looking above it, the ball goes straight through inertial space because no forces act on it, but as it goes through the surface it is not rotating. It appears to go off to the right though. But if you were attached to this ball, you would actually see it curve. The Coriolis Force

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EPS 102 lecture 16 - EPS 102 lecture 16 Tuesday March 16th...

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