Weather Map

[asterroc]

Anyone *cough*meredithanne42*cough* know what the yellow line with half-circles over west Texas means? I've never seen it before.



ETA: And while I'm at it, why does it make a difference if a cold front moves under warm air, or a warm front moves over cold air? They're the same except for the stationary ground under them, why does that affect them?

Comments

[sammka.livejournal.com]

Tornadoes!

(I just made that up)

[zandperl.livejournal.com]

Nah, those're supposed to be along the Missouri River today, and I think that's more North and East.

[sammka.livejournal.com]

A more educated guess:

from looking at the other maps, absolutely nothing interesting is happening in that same area. Perhaps it's a high pressure system.

[zandperl.livejournal.com]

Nope, high pressure systems are marked with an H, lows with an L, and various other things with other symbols. I could probably dig it up more deeply elsewhere, but I'm lazy. :-P

[sammka.livejournal.com]

(that was probably wrong too)

As for moving air: maybe it's the airplane effect, in which laterally-moving air has less up/down pressure?

[zandperl.livejournal.com]

Which begs the relativity question I was implying with my ETA. I guess the simplest answer is since we're stationary on the ground, it'll make a difference how fast things are moving relative to us. But if we could put a state on wheels and move it under the fronts, we should get the same effect. Ooh, "States on Wheels, coming to an arena near you!"

[meredithanne42.livejournal.com]

I'm thinking it's probably a "dry line," but I will check.

[meredithanne42.livejournal.com]

Yep! It's a dry line. Read all about it here: http://www.stormtrack.org/library/forecast/dryline.htm

:)

[zandperl.livejournal.com]

Huh. Hadn't heard of it. Is it a rare phenomenon? Hm, perhaps the link says. :-P

[meredithanne42.livejournal.com]

Regarding the warm/cold fronts... I think the major difference is what happens to the air masses when they meet. A cold front, as you know, involves a cooler air mass approaching a warmer one--the colder air mass undercuts the warmer air mass, because of their density differences. With the warm air being displaced upwards, the resulting atmospheric condition tends to be unstable. High clouds can build, thunderstorms, a gradient that favors convective uplift, etc. Cold fronts also tend to move more quickly and are in general more intense, I guess simply because of what happens when warm air is displace upwards.