By: Beatrice Bea Nash and Bethany Cates
1 Introduction
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Using the equation for the deformation radius, given in 3.3, we calculate the predicted radius of deformation to be around 20 centimeters, or half of the width of the tank. Since the boundary of the front extends all the way to the outside of the tank, about 3/4 of the distance to the bottom of the tank, the actual radius of deformation for this front is slightly larger than this prediction. Therefore, we see the slope of the front decrease frontal boundary is horizontal towards the edge of the tank, as it has no more room to spread outwards.
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Figure 4.5: azimuthal velocity as a function of radius for particles tracked at the surface of the frontfrontal boundary.
These particles are more difficult to track, hence the tracks are shorter, and the concentration of dye and particles at the center of the front makes it impossible to track the particles for very small radii accurately. Still, it is clear from this plot that the azimuthal velocity of the fluid at the frontal surface boundary has the same overall radial dependence as that of the fluid at the free surface for large radii. However, we see only a small peak at 5cm, unlike the very defined peak at that radius for the velocity of the fluid at the surface.
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Figure 6.1: Left: Air temperature at 500mb for the Northern hemisphere in January. The change in temperature between the cold air at the North pole and the warmer air near the equator occurs only in the midlatitudes; otherwise, there is essentially no little meridional temperature gradient. This is because of the same phenomenon driving what we saw in the lab; Coriolis forces due to Earth's rotation keeps the dense cold air at the poles in fronts. Right: Potential air temperature as a function of pressure and latitude. Potential temperature is preserved under adiabatic processes and is therefore a better indicator of heat transport than temperature. Between 20 and 60 degrees latitude, there is a sharp potential temperature gradient where the polar front and warm air from south southern latitudes meet , creating at a positive slope similar relative to that seen in the lab experimentpoles.
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Figure 6.2: Left: Where the temperature gradient is largest, the wind speeds are also greatest. At around 60 degrees latitude, this temperature gradient produces the polar jet stream, which consists of powerful westerly winds. Just as in the lab, the boundary of the dense air in the polar cell forms a sloped boundary with the less dense warm air from the Ferrel cell. Right: Wind speed as a function of pressure and latitude, showing how both powerful and contained the polar jet stream is.
PolarFront_fastloop_smaller.gif
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