UPDATE: 8:00 p.m. Tonight's launch attempt was scrubbed due to bad weather. No word yet on when they will try again. Earlier post follows:

Sky watchers in the mid-Atlantic region may get a look at an odd artificial cloud Tuesday night after it's released from the fourth stage of a rocket set for launch from NASA's Wallops Flight Facility on the Eastern Shore.

The cloud of aluminum particles from the rocket's exhaust is expected to provide scientists with insights into the physics of "noctilucent clouds," the highest natural clouds (around 50 miles up) that form in the Earth's atmosphere. That's a NASA photo of such clouds, above.

The experiment, called "Charged Aerosol Release Experiment" (CARE), is being conducted by the Naval Research Laboratory and the Pentagon's Space Test Program. Also involved are NASA, the University of Michigan, the Air Force Research Laboratory, Clemson, Stanford and Penn State universities, the University of Colorado and MIT.

The launch window for the experiment opens at 7:40 p.m. Tuesday, and closes at 7:57 p.m. Weather forecasters gave the launch a 60 percent chance of favorable weather. Clear skies are needed up and down the coast to provide multiple camera locations with a view of the cloud.

Backup dates for the launch are each evening Sept. 16-20, but the weather is expected to deteriorate this week. The next opportunity would come next month.

The experiment is being carried by a 65-foot Black Brant 12 rocket, a sub-orbital vehicle used frequently by scientists at Wallops. The rocket is programmed to climb 180 miles above the Earth - much higher than the altitude of natural noctilucent clouds - and 98 miles down range (east) from Virginia's Eastern Shore.

Observers should watch for the cloud to be released about six minutes after launch. If skies are clear, the sinuous white cloud should become visible in the eastern sky after its release.

To follow the launch via Webcast, http://sites.wff.nasa.gov/webcast.  For Twitter updates, go to http://twitter.com/NASA_Wallops. Or call the recorded updates at 757-824-2050.

And as always, any WeatherBlog readers who see it are invited to come back here and leave comments describing the event for those who miss it.