Naked Science Forum

Life Sciences => The Environment => Topic started by: Martin Quin on 26/07/2008 15:07:48

Title: Why do cold fronts move faster than warm fronts?
Post by: Martin Quin on 26/07/2008 15:07:48

Martin Quin asked the Naked Scientists:

Hello,

Right now I'm taking meteorology, and I have a question my professor
can't answer.  Why are cold fronts faster than warm fronts?  Thank you for
your time,

Martin Quin
What do you think?

Title: Why do cold fronts move faster than warm fronts?
Post by: paul.fr on 26/07/2008 15:22:20

You need to look at your models / charts for occlusions, and tie them in with what a cold front looks like from a cross section view.

It moves faster because the makeup of a cold front itself, your cold front has a leading edge (wedge shape)of cold and denser air. This air pushes up the warmer lighter air. If you look at your model of a warm front, you will see that it is like hitting a brick wall - the warmer lighter air has a harder time trying to lift the colder denser air, thus slowing it down.

Cold fron can move at upto 20mph faster than a warm front!

If i get time i will post some diagrams later.

Title: Why do cold fronts move faster than warm fronts?
Post by: DoctorBeaver on 26/07/2008 15:46:30

That's interesting, Paul. I never knew that.

Title: Why do cold fronts move faster than warm fronts?
Post by: paul.fr on 26/07/2008 19:20:37

Quote from: DoctorBeaver on 26/07/2008 15:46:30

That's interesting, Paul. I never knew that.

Ahh Shucks,  [:I]

Ok, I tried to do the drawing but as usual the turn out very poor when trying to use a mouse. But, I did find this pretty helpful page:
Norwegian Cyclone Model (http://www.srh.weather.gov/srh/jetstream/synoptic/cyclone.htm)

Title: Why do cold fronts move faster than warm fronts?
Post by: paul.fr on 26/07/2008 19:22:17

Images from the above link:


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Title: Why do cold fronts move faster than warm fronts?
Post by: paul.fr on 26/07/2008 19:32:55

To add to the text from that link:

Once this low has reached the warm sector stage (the 3rd image) it continues to develope, the warm sector increasing in amplitude and becoming narrower. This is where the cold from catches up with and eventually overtakes the warm front.

In the fourth image you will notice that the warm air does not now extend all the way to the centre of the low, this is due to the cold front overtaking the warm, and you have an occlusion developing.

Title: Why do cold fronts move faster than warm fronts?
Post by: paul.fr on 26/07/2008 19:36:36

These images are also from the above link, and are the best i have seen. The show a 3d view of the waves, and are really simple to view then understand.

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Title: Why do cold fronts move faster than warm fronts?
Post by: paul.fr on 26/07/2008 19:37:21

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