Jump to content
Holidays
Local
Radar
Pollen

Archived

This topic is now archived and is closed to further replies.

feb1991blizzard

Angular Momentum

Recommended Posts

I have done a fair bit of reading but i still cant grasp anglular momentum and more importantly how it affects pressure patterns, i would be very grateful if someone could explain in laymans terms, i dont expect to be able to understand it to the level that some do on here, i would like more than anything just to be able to understand the charts that GP posts on here how they affect our weather, one of the first questions i would ask is does an increase in GLAAM increase the chances of the azores high further east and does it affect our weather differently in summer to winter.

Share this post


Link to post
Share on other sites

Deleted..

I was just about to thank you for the reply, i have had a fair bit to drink right now so i was going to try and get my head around it tomorrow, i have now realised you have deleted it, how come?

Share this post


Link to post
Share on other sites

The anglular acceleration is connected and arises from the fact that, when circling around an axis, the air parcel changes its velocity. As you may already know, the change in velocity can be accomplished in two ways: by changing its magnitude or its direction. In the case of anglular acceleration we have the second option. The angular acceleration is given by the expression v^2/R, where V is the linear velocity and R - the radius of Earth. On the other hand: the momentum is simply the mass of an object multiplied by its speed. This gives m.w (where w is omega, or angular speed, the connection between the angular speed and the linear speed is V=R.w). What is more importantly, the angular acceleration (not momentum) and the Centripetal force make a clear reference to the Centrifugal force (the opposite of Centripetal force = m. v^2/R where v^2/R, as I wrote, is the angular acceleration).

These are the basics of angular momentum, angular acceleration and the two forces. Fruther investigation opens the doors into the dynamical meteorology which gives us an opportunity to make use of these assumption and describe the dynamics of the fluid. Shortly, the centrifugal force helps us to describe the Coriolis force and complete the set of equotions that describe the motion of the fluid.

If you have any questions, do not hesitate to ask me. I may be able to write down all these things on a sheet of paper and post it there. And finally: I hope this could have helped you smile.png

Share this post


Link to post
Share on other sites

I was just about to thank you for the reply, i have had a fair bit to drink right now so i was going to try and get my head around it tomorrow, i have now realised you have deleted it, how come?

We won't go into that fb but this is what I posted.

The General Circulation

A second controlling factor is the angular momentum of the earth and its atmosphere. This is the tendency for the earth's atmosphere to move, with the earth, around the axis of rotation. Angular momentum is proportional to the rate of spin (that is the angular velocity) and the square of the distance of the air parcel from the axis of rotation. With a uniformly rotating earth and atmosphere, the total angular momentum must remain constant (in other words, there is a conservation of angular momentum). If, therefore, a large mass of air changes its position on the earth's surface such that its distance from the axis of rotation also changes, then its angular velocity must change in a manner so as to allow the angular momentum to remain constant. Naturally, absolute angular momentum is high at the equator and decreases with latitude to become zero at the poles (that is, the axis of rotation), so air moving polewards tends to acquire progressively higher eastward velocities. For example, air travelling from 42 to 46° latitude and conserving its angular momentum would increase its speed relative to the earth's surface by 29 m S-1. This is the same principle that causes an ice skater to spin more violently when her arms are progressively drawn into the body. In practice, this increase of air-mass velocity is countered or masked by the other forces affecting air movement (particularly friction), but there is no doubt that many of the important features of the general atmospheric circulation result from this poleward transfer of angular momentum.

Source:

Roger G. Barry and Richard J. Chorley, "Atmosphere, Weather and Climate", seventh edition, Routledge.

Share this post


Link to post
Share on other sites

Thanks very much for the replies, i will try to get my head around but will probably take time as i have some stress right now but inevitably will need to ask more questions at a later date.

Share this post


Link to post
Share on other sites

  • Recently Browsing   0 members

    No registered users viewing this page.

×