So I read something which I definitely couldn’t understand. It’d be very helpful if somebody could explain it to me in a simple manner-
“The coriolis force acts perpendicular to the pressure gradient force. The pressure gradient force is perpendicular to an isobar. The higher the pressure gradient force, the more is the velocity of the wind and larger is the deflection in the direction of wind. As a result of these two forces operating perpendicular to each other, in the low-pressure areas the wind blows around it. At the equator, the coriolis force is zero and the wind blows perpendicular to the isobars. The low pressure gets filled instead of getting intensified. That is the reason why tropical cyclones are not formed near the equator.”
I’m quite confused because aren’t isobars just lines drawn to show the areas with same atmospheric pressure?
In: Earth Science
Your last sentence is correct. An isobar is a line along which the pressure is the same. Assuming it’s not an entire isobaric region (entire area is same pressure), then one side of the isobar is higher pressure than the other. This relationship *should* hold relatively true along the isobar. That means that there is an air pressure gradient across the isobar. That pressure gradient is the basis for air pressure to exert a force, since fluids at higher pressure flow towards low pressure zones to establish equilibrium. Since the isobar is the line of same pressure, the flow *should* be perpendicular to (straight across) the isobar, as one side presses directly into the other at all points.
The Coriolis force isn’t explained in this passage, but it is mentioned as acting perpendicularly (straight across) the pressure gradient force. This means that it acts along the isobar, as both the isobar and Coriolis force are perpendicular to the same thing: the pressure gradient force. Now since the Coriolis force is a force, it will affect how the wind blows. Normally, the wind blows purely based on pressure gradients. It states that the Equatorial region is one such example. This means that any pressure differences are quickly neutralized, as high pressure flows into low pressure.
However, in non-Equatorial regions where the Coriolis force is not zero (based on their assumption/prior work), the wind doesn’t act like that. The air flowing from the high pressure region into the low pressure region is deflected somewhat by the Coriolis force to the “side” (along the isobar). Therefore, the low pressure region isn’t immediately filed by air from the high pressure region, and it continues to generate the pressure gradient force. Since these pressure gradients are never settled and instead constantly exist/grow, there is always wind of varying strength in non-Equatorial regions, which is what allows strong storms like cyclones to form.
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