Sunday, September 23, 2007

Lift over the ocean?!?!?!

This is a little off-topic, but all glider pilots are interested in weather, right?

Yes, there can be lift over the ocean, but not the kind you'd want to fly in! This weekend we were camping at a Southern California beach, and a building thunderstorm went by about 2-3 miles offshore. This storm generated about 7 waterspouts that we could see! This picture shows four of them. (Click any pic for a larger, hi-res image.)
















A waterspout is just a tornado over water, and tornadoes are swirling, upward-moving air. As I understand it, the sun heated the water and caused intense evaporation, then a cold air mass must have moved over it to cause the condensation. There must have been quite a temperature gradient to cause such intense uplift. Here's a closer shot of a typical funnel cloud... I hope the picture quality allows you to see the little disturbance at the ocean surface as well. Not a good place to be in a boat!

An odd feature we noted is the squared-off "notch" in the cloud on both sides of each funnel. This must indicate a region a little cooler, where the air reaches the condensation point a little earlier (lower). I assume it's circular (disk-shaped), I don't know if it's rotating or not. This may be a form of "wall cloud". You can see a disk around each funnel in the top photo. Also, the funnels seemed to be fairly evenly spaced, so there must be some relationship to the width of the thermals, like in a "cloud street".
















Three or four of the funnel clouds stretched all the way to the surface, getting thinner as they went. If you look carefully, you can see that there's an empty core inside the dark tendril, I assume caused by centrifugal force. This shot came out well because of the blue sky behind the waterspout.
























And here's a double shot:
















We watched this activity for about 35 minutes. The waterspouts eventually died out as the storm moved to the north. The storm transitioned from the cumulus stage (uplifting) to the mature stage (collapsing into rain). I think the north part came ashore as the rain came down, and no waterspouts reached the land that we could see.

3 comments:

smithcorp said...

Hi Roger - I'm enjoying your blog! I'm learning to soar too, here in the antipodes. I start a week's intensive training next month.

Thanks for the well-written and informative blog and please keep it up.

smith

Roger said...

Thanks! I try to write after every day of soaring (about twice a month), or if anything else comes up that's of interest. I have no idea how many people read it, so I do appreciate comments.

smithcorp said...

Cheers - do you find that amount of flying is sufficient to develop and keep your skills from getting rusty?

After my week's flying I will have about the same level of potential flying and wouldn't want to to stall (figuratively). I'd appreicate your advice.