An interesting weather phenomenon

[grmorton]

I have been incredibly busy. Old job, new startup, and at my ranch, both corn and grape harvest--last two weeks I made my very popular home-made grape jelly--last week with my grand-daughter, this week alone.

Anyway, I have noticed an interesting meteorological phenomenon. I looked at the internet to see if anyone else had ever seen such a thing on radar and I couldn't find it. At the outset, I will say that I know what is causing this, and will post as much information as I got in the order and timing at which the information became available to me. I want to provide a puzzle to see if anyone else knows what causes it. I won't answer guesses until my next post.

In the pictures below which can be loaded into powerpoint and animated, you will see two expanding circles. One near Beaumont, TX, and the other near the NW corner of the ring road around Houston. The radar echoes expand with time. I hope the pictures come out in order as I load them. If not, look for the tiny time stamp on each pic at the top and then look at them in order.

Have fun with this 'mystery'. I will be back tomorrow with a wee bit more information.

[shunyadragon]

Interesting. I do not know what is causing this, but I will guess it has to do with the city itself, possibly related to heat.

[grmorton]

Interesting. I do not know what is causing this, but I will guess it has to do with the city itself, possibly related to heat.

When I first saw that phenomenon, I had an immediate guess (I will tell later whether or not I was correct in that guess)


I was looking for a picture of me and my grand-daughter making the grape jelly I mentioned in my last note. Here it is. the mess is behind us in all its glory. Life is lots of fun when one has grandchildren to help them make Jelly.

[Crow]

Hmmm.

Pollution and/or heat are being read as humidity by instruments and giving a false impression of precipitation over the cities?

[NeilUnreal]

First, I'm jealous of your grape harvest. For some reason, for the last few years, ours have ripened out of sync (on the same vine!). So we have a trickle of grapes all summer, but not enough at one point to make canning worthwhile. FWIW, they are concord grapes and still taste fantastic.

WRT the radar images: I like the ideas about convective bubbles around heat islands.

But first, I'd want to rule out something intrinsic to the equipment, like artifacts from the automatic gain control or some other feature of the radar. (e.g. Automatic changes in the frequency, phase, etc.; changes in the image processing, etc.) In terms of image processing, I assume this is a composite image from several radar, and so it might reflect changes in local gain control, etc.

Second, like Crow, I'd want to make sure that it isn't an artifact of interaction between the radar and precipitation or something else. (Possibly in interaction with #1 above. For example, differences in signature due to doppler direction of raindrops, orientations in their shape, angle to the droplets as ceiling height changes, etc.)

Barring those two, I'd probably guess it's convective and related to a heat island.

-Neil

p.s. I've seen similar things on weather radar, but have never really investigated it.

[grmorton]

First, I'm jealous of your grape harvest. For some reason, for the last few years, ours have ripened out of sync (on the same vine!). So we have a trickle of grapes all summer, but not enough at one point to make canning worthwhile. FWIW, they are concord grapes and still taste fantastic.

WRT the radar images: I like the ideas about convective bubbles around heat islands.

But first, I'd want to rule out something intrinsic to the equipment, like artifacts from the automatic gain control or some other feature of the radar. (e.g. Automatic changes in the frequency, phase, etc.; changes in the image processing, etc.) In terms of image processing, I assume this is a composite image from several radar, and so it might reflect changes in local gain control, etc.

Second, like Crow, I'd want to make sure that it isn't an artifact of interaction between the radar and precipitation or something else. (Possibly in interaction with #1 above. For example, differences in signature due to doppler direction of raindrops, orientations in their shape, angle to the droplets as ceiling height changes, etc.)

Barring those two, I'd probably guess it's convective and related to a heat island.

-Neil

p.s. I've seen similar things on weather radar, but have never really investigated it.

I want to thank Crow and Neil for guessing. Science requires a hypothesis, and often the first hypothesis is a guess. Case in point, my first guess as to what these rings are: I thought it was some sort of downdraft. Others in my office said that sounded reasonable.

So the next day when I got to work I saw the first three pictures. Notice that the circles are radiating from the same place. That made it clear that both Crow and Neil's guesses are close to the truth, some sort of heat source affixed to specific spots on the earth.

Then the question became, what were they? I didn't think much more about it that day but two days later when I next looked at the radar I saw the next set of pictures dated July 29th. The circle that radiates from the NW corner of Houston's Beltway road (the circle on the left), was the key to understanding what was happening. I drive by that corner every day on my way to work. There is a power plant at that spot--a coal-fired power plant. It appears that everyday about 6:30am, when Houston wakes, up and the power plant must rev up to meet the electricity demands of a waking city, the plume of heat from the powerplant goes up and causes a ring of condensing steam--a vortex of cloud that spreads out.

I have looked at other radar sites and saw one east of Dallas, at Fort Campbell, Kentucky, and I think I saw part of one at New Orleans. It doesn't seem to be a phenomenon everywhere every morning, but it has been there in Houston every morning that I have looked.

Scientific observations are most fun when they show something that one hasn't ever observed before. I had never noticed those rings before until Monday week.

Anyway, that is the mystery, solved with something quite mundane. I would have loved it if it was an X-file landing site, but no such luck

WRT Neil's grapes. That is awful that they string you along all summer. I will have enough grapes next week (for the third week in a row), to make another 10 jars of jelly. But having now more than I can eat over the next year, I will let the birds have what is left.

[NeilUnreal]

Good analysis; likely cause. On still mornings -- after the previous afternoon's conventive churning has calmed down -- it can take very little perturbation to create local meteorological effects.

-Neil

[USIncognito]

I was going to guess Chili Cookoff until you mentioned it was a recurring event.

[grmorton]

I was going to guess Chili Cookoff until you mentioned it was a recurring event.

That would do it. :-)

[MooseOnTheLoose]

We had an unusual weather phenomenon here in Scotland.

It didn't rain for a whole day.

[shunyadragon]

We had an unusual weather phenomenon here in Scotland.

It didn't rain for a whole day.

Don't go out without your umbrella, or you will be accused of not being a true Scotsman..