From: pauld@exploratorium.edu
Date: Sat Apr 05 2003 - 15:22:51 PST
Message-Id: <200304052322.h35NMno10990@isaac.exploratorium.edu> From: pauld@exploratorium.edu Subject: Re: pinhole Winds and general relativity Date: Sat, 5 Apr 2003 15:22:49 US/Pacific
Hi Jhumki
1. The surface of the earth at the equator moves fater ( at 1000 mph) than the
surface at 45 degrees north (700 mph). Air at the equator rises due to solar
heating travels north and descends at about 30 north latitude then returns along
the surface to the equator. The slow eastyward velocity air at 30 degrees north
moves over the place where the earth's surface is going east at 1000 mph and
becomes and easterly wind. This is called the coriolis effect.
similarly air at the pole cools and descends. moves down to 30 N latituide rises
and returns. also creating easterlies.
Between 30 N and 609 N a cell in the atmosphere called a hadley cell is driven
into vertical rotation by the other two cells. It rises at 60 N and descends at
30 N creating prevailing westerlies by the same coriolis mechanism.
2. Yes glaxies create gravitational lenses due to both their visible stellar
matter and also dark matter. It's one of the proofs that dark matter exhits.
3. everything with energy has real mass, so gravity acts on everything. The
confusing concept is the one of rest mass. Photons have a zero rest mass, yet
they are never at rest. Real photons have real mass and fall under gravity. They
fall exactly twice as much as predicted by Newton's l;aws which is why we need
general relativity.
4. The best books on relativity both special and general are Clifford Will Was
Einstein Right? 2nd edition and Spacetime Physics by Ed Taylor.
Paul D
> A few questions:
>
> 1. Why do the equatorial winds blow from east to west? Is it because the
> earth rotates from west to east? So then, does the earth's atmosphere not
> move with the earth's lithosphere?
>
> 2. Is there evidence of gravitational lensing caused by dark matter?
>
> 3. Does gravity act on massless particles such as photons? If so, is there
> a reason? I don't understand the concept of "effective mass." How can
> gravity act on effective mass?
>
> 4. Do you have recommendations for a good introductory book to general
> relativity?
>
> Thanks!
> Jhumki
>
>
>
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