Coriolis Force

[sdfcvoh]

I'm having a REAL numb-skull moment here.....I've been trying not to post this question but I can't avoid it any longer.

I'll set it up first. I do understand what Coriolis effect is. Its always made perfect sense. But.... here's the deal. I'm having a serious problem grasping why it has the effect it does on some weather circulation.

Let me pose my dilemma.... as cold air descends at (e.g.) the polar cell and the earth is rotating eastward, that descending air is deflected to the right (seemingly westward) on its trip to the South. I've got that. It makes perfect sense.... Mr. Coriolis is smiling in his grave.

What I'm missing is this: Why does ascending air seem to rotate Eastward? I just can't grasp it. It seems to me that it would want to rotate Westward also, and this is where I really am lacking. Its got to have something to do with Newton, and possibly that the ascending warmer air being less dense than the descending cooler air gets the shorter end of the stick and is pushed that direction partially because of Newton....but I just don't feel like I've grasped it enough to be able to answer a student asking, "why doesn't the ascending air deflect westward, too?" I really don't want to have to answer with the textbook, "Coriolis effect/force causes the air to deflect to the right...." when I don't completely understand part of it myself.

Okay....thanks for reading!

[tgrayson]

Originally Posted by sdfcvoh

I'm having a serious problem grasping why it has the effect it does on some weather circulation.

You're kinda blurring together two different aspects of the same thing. First, rising and descending air do one thing, and air moving laterally across the earth do other things. When air is ascending or descending AND moving laterally along the earth, you will get a blend of those effects.

For instance, the air rising at the equator wants to turn towards the west due to the rising, however, it wants to turn towards the east due to its moving north. Supposedly, the rising part only produces a small force, so majority of deflection is towards the east.

When some of the literature describes ascending or descending air, they *may* be merely describing which body of air they're talking about, rather than describing the relevant direction of motion.

[sdfcvoh]

I follow you there. But I'm still trying to figure this out....

Originally Posted by tgrayson

You're kinda blurring together two different aspects of the same thing. First, rising and descending air do one thing, and air moving laterally across the earth do other things. When air is ascending or descending AND moving laterally along the earth, you will get a blend of those effects.

For instance, the air rising at the equator wants to turn towards the west due to the rising, however, it wants to turn towards the east due to its moving north. Supposedly, the rising part only produces a small force, so majority of deflection is towards the east.

When some of the literature describes ascending or descending air, they *may* be merely describing which body of air they're talking about, rather than describing the relevant direction of motion.

[Flyin_bryan]

Schematic representation of inertial circles of air masses in the absence of other forces, calculated for a wind speed of approximately 50 to 70 m/s. Note that the rotation is exactly opposite that normally experienced with air masses in weather systems around depressions.