Question on Fronts

[uwochris]

Hey guys,

Is it possible that cold/warm fronts are ever associated with High pressure systems?

I figure that the forecasters never put the fronts on weather maps because there would not be any active weather associated if under the influence of a high. I understand that with Lows, you get the cyclonic flow, with the warm and cold air bulging out to form the fronts. However, with a high, is it not still possible to have cold/warm air masses advancing towards another region, and hence, have fronts associated with them?

TIA.

 

[avbug]

Chris,

A common misconception is that a high spells good weather, while a low spells bad. This is often not the case. While a low is often associated with increased moisture and activity, it's more wives tale than fact.

Poor weather can accompany both. Fronts are very often associated with high pressure. Remember that a front represents the boundary of different air masses, and regardless of weather it's a high or low, that air mass will typically be bounded by a front on one or more "sides."

The location and activity of these fronts, as well as the nature of the airmasses that the front defines, determine the weather to be associated in advance of, in, and behind the front.

 

[tarp]

Chris,

I'm going to make an assumption that this is the very same question one very smart student asked of me.

He also brought me a weather map and asked the same question. His "observation" was that bad weather and fronts were shown on the map as Low Pressure systems with cold and warm fronts coming out of them. (A good picture is that the "L" in the low pressure looked like a kite with a tail coming out of it.)

I laughed to myself because it was like looking at a Rorschach Test inkblot. My vision was that the Cold Front in those pictures was a picture of two High Pressure systems with a Low Pressure and a cold front trapped in between. My student's picture was of a messy Low Pressure and all this weather with two High Pressures on either side and no weather.

I loved it. It is the common problem with anything science related. Chicken and the Egg type stuff. Does the chicken make the egg or does the egg make the chicken?

Let's talk science and something different as an example of my thinking and then see if it helps you.

Niagara Falls is a beautiful site. All that power of water cascading down in a thunderous roar. But how does it work? Basically all the water in Lake Erie is trying to get to Lake Ontario but it is blocked by a granite dam made of the land bridge between Hamilton, Ontario and Buffalo. There is no doubt that Lake Erie has tons and tons of water but is tranquil enough that you could go to the beach and swim in it (Probably only from August 15 to August 30th - joke). And Lake Ontario has tons and tons of water.

In science, Lake Erie has "potential energy". Lake Ontario has "potential energy" (that ultimately goes out the St. Lawrence River to the ocean). But Niagara falls is a pure show of "Kinetic" energy.

This is how I view High Pressures, Low Pressures and fronts. The High Pressure is like a lake. Big body of fluid with all these currents (winds) and eddys. There's a lot of energy because it is, well, under "high" pressure. Now a Low Pressure is like the river at the base of Niagara Falls. Not very big, but has received an awful lot of energy from the water coming out of Lake Erie. The Falls like a "weather front" are a result of the water in Erie trying to get to Ontario.

Now the Lake and Falls example is pretty extreme when compared to weather. So let's do this. An earthquake hits my land bridge and wipes out the granite formation blocking Lake Erie and Lake Ontario. What's going to happen? Well there will be a factor of time. But basically all the water in Erie will flood into Ontario until the two become equalized, right? During the collapse of the land bridge we had two high pressure systems, Erie and Ontario. Ontario has slightly lower elevation and hence slightly lower pressure. But when the land bridge disappears a huge low pressure forms in the water rushing to equalize and the torrent of water is a huge flood.

So you're a news reporter, what happened? Did Lakes Erie and Ontario equalize into one lake? Or, did a flood just occur? Pretty easy to point out the flood.

Pretty easy to pinpoint the center of the Low Pressure and the fronts that form. Hurricane = big low pressure, tornado = little area of intense low pressure. When dealing with things in nature just remember that nature abhors a vacuum. If there is a low pressure thing with a high pressure next to it - the high pressure stuff will try to run to the low. If there is a thing with heat and a thing that is cooler next to it, the heat will try to dissipate. The thing with high pressure or high heat has energy. The thing with low pressure or cool temps has less energy and will be a receiver of energy from an other source.

So flip your view of the Rorschack for a second and look at the spaces instead of the lines. But remember, like the chicken and egg you have to look at both. You are right, when the Low Pressure gets spinning, all that spinning creates its own energy and causes things to happen. The atmosphere is a closed system. Every "push" has a "pull" someplace. High pressure runs to Low pressure. Low pressure air starts spinning. Spinning air creates heat. Hot air rises, cold air falls. Cold air cools the surface of the earth creates High Pressure system. Oh dang we've started all over again. (Example highly simplified)

 

[Iceman21]

I must say tarp that is a very good example that illustrates weather systems at a basic level.

Now if I could only get the advanced understanding of weather down pat. I think it is going to take a few years

 

[Cardinal]

Now if I could only get the advanced understanding of weather down pat. I think it is going to take a few years

Or a few decades A few years a go when faced with precious little weather knowledge I decided that at the very least I would look at a national weather map every day, and correlate that with what I saw out the window, or even better flew around in. At the very least when you do have to make a flight in shoddy conditions you can readily equate what you see on the map or in the forecast with the conditions you can expect in the air.