Low pressure.
Moderator: S2k Moderators
-
- Professional-Met
- Posts: 11430
- Age: 33
- Joined: Sat Dec 24, 2005 9:00 pm
- Location: School: Florida State University (Tallahassee, FL) Home: St. Petersburg, Florida
- Contact:
Re: Low pressure.
I wouldn't be so sure about that...
First, I'm going to split a technical hair with you. Low pressure does not necessarily mena a low pressure center--with a closed isobar and "spin". As such, low pressure can most certainly cross the equator. Take, for instance, monsoonal troughs--they generally lie near the equator and can travel north and south as the seasons progress and most certainly cross the equator.
Next, don't overestimate coriolis near the equator. It's very small, and increase very little as you move away from the equator (when near the equator, the diameter of the earth at any latitude does not decrease much vs the diameter at other, nearby latitudes). Hence, a low pressure center--with spin--would actually only undergo a very small change in coriolis--from very small on one side of the equator, to "none" at the equator, to very small in the other direciton on the other side.
At such low latitudes, with such small coriolis, other forces can come into play in order to set things spinning (and keep them spinning). For instance, occasionally we see a TC form at very low latitudes--often, the "spin" in these TCs comes from some existing source of vorticity and centrifugal/centripetal effects. Since coriolis plays a neglible role in the rotation to begin with, a loss of, or a change to the (already very small) coriolis force might not have quite as dramatic of an effect as you would think.
WJS3
First, I'm going to split a technical hair with you. Low pressure does not necessarily mena a low pressure center--with a closed isobar and "spin". As such, low pressure can most certainly cross the equator. Take, for instance, monsoonal troughs--they generally lie near the equator and can travel north and south as the seasons progress and most certainly cross the equator.
Next, don't overestimate coriolis near the equator. It's very small, and increase very little as you move away from the equator (when near the equator, the diameter of the earth at any latitude does not decrease much vs the diameter at other, nearby latitudes). Hence, a low pressure center--with spin--would actually only undergo a very small change in coriolis--from very small on one side of the equator, to "none" at the equator, to very small in the other direciton on the other side.
At such low latitudes, with such small coriolis, other forces can come into play in order to set things spinning (and keep them spinning). For instance, occasionally we see a TC form at very low latitudes--often, the "spin" in these TCs comes from some existing source of vorticity and centrifugal/centripetal effects. Since coriolis plays a neglible role in the rotation to begin with, a loss of, or a change to the (already very small) coriolis force might not have quite as dramatic of an effect as you would think.
WJS3
0 likes
Return to “Got a question? I'm listening”
Who is online
Users browsing this forum: No registered users and 14 guests