Showing posts with label cloud. Show all posts
Showing posts with label cloud. Show all posts

Wind Shear Accident Was Catalyst for Technology

http://nasa-satellites.blogspot.com/
Gray Creech of NASA's Dryden Flight Research Center can remember August 2, 1985, as if it was yesterday. On that day 25 years ago the public affairs specialist was a young U.S. Air Force airman heading home on leave to North Carolina, flying out of Dallas Fort Worth International Airport. "I was just minding my own business, sitting at the end of the runway aboard the second airplane lined up to take off," said Creech. "I had a window seat and was looking out the window when I noticed some really, really black thunder clouds at our end of the runway. Then I saw orange, extremely bright orange, light. My brain didn't register what I was seeing."

What Creech saw was Delta Flight 191 as it crashed on landing. "It was like a slow motion thing. There was the initial fireball, but then as the airplane rolled over, breaking apart and slowing down, the fire caught up with it and enveloped it," added Creech. "It all came to a halt directly even with my window, across the other side of the runway in the grass. As soon as the movement stopped, the rain hit. It was like a wall of rain and the fire quickly became a smoke ball, black and white smoke mixed."

"I remember our pilot coming over the intercom and saying something to the effect ladies and gentlemen, there has been a tragedy and I'm sorry, but we can't return to the terminal and let anyone deplane," said Creech. "Of course that was the last thing any of us wanted to hear, because anybody who saw that wasn't wanting to stay on their plane and go flying. I know I didn't." One hundred and thirty four people of the 163 on board the Delta Lockheed L-1011 and one person on the ground died that day, in part because of a powerful thunderstorm microburst-induced wind shear, a rare but potentially deadly downdraft.

Puff, the Magic Dragon?

cloud
A dragon-shaped cloud of dust seems to fly with the stars in a new image from NASA's Spitzer Space Telescope (bottom). In visible light (top), the creature disappears into the clouds perhaps it's "frolicking in the autumn mist" like Puff, the Magic Dragon, from the famous Peter, Paul and Mary song. The infrared image has revealed that this creature, a dark cloud called M17 SWex, is forming stars at a furious rate but has not yet spawned the most massive type of stars, known as O stars.

Such stellar behemoths, however, light up the M17 nebula at the image's center and have also blown a huge "bubble" in the gas and dust that forms M17's luminous left edge. The stars and gas in this region are now passing though the Sagittarius spiral arm of the Milky Way , touching off a galactic "domino effect." The youngest episode of star formation is playing out inside the dusty dragon as it enters the spiral arm. Over time, this area will flare up like the bright M17 nebula, glowing in the light of young massive stars.

An older burst of star formation blew the bubble seen in the region to the far left, called M17 EB. The visible-light view of the area clearly shows the bright M17 nebula, as well as the glowing hot gas filling the "bubble" to its left. However the M17 SWex "dragon" is hidden within dust clouds that are opaque to visible light. It takes an infrared view to catch the light from these shrouded regions and reveal the earliest stages of star formation.