Can someone explain upper level diffluence?

[It's Always Sunny]

Could use a bit of a brush up on upper level diffluence

[tornadojay]

Here is a good article on diffluence. It also talks about the differences between diffluence and divergence. Diffluence is simply the spreading of wind vectors, which can be found by looking at the spread of geopotential heights at a given pressure level. Diffluence not only causes convergence (due to air piling up in a given spot), but also divergence due to a spread of wind vectors. Therefore, alone, it does not cause rising air motions as the two generally cancel each other out. This is where the importance of vorticity comes in.

Positive Vorticity Advection (PVA) will lead to a net result of rising air as divergence is overpowering. Just east of a vorticity maximum is generally an area of high wind speeds, followed by a relative minimum right under the vort max. The net result is a loss of mass in that area as air is moving out greater than the rate it is moving in. Also, PVA leads to a curvature in the height field which will cause divergence due to spread in the wind direction.

http://www.theweathe...ced/habyextra6/

[It's Always Sunny]

Thanks for the explanation, I appreciate it.