F/A-18 Hornet: Oregon International Air Show

Posted on Saturday, Mar 19, 2011

Saturday, August 29, 2009

If you’ve followed my previous posts about the 2009 Oregon International Air Show, you may have noticed that the skies have been awesome. It would be hard for me to imagine more perfect weather for an air show than what we experienced over the course of the weekend: cool temps combined with layers of huge, three dimensional clouds that ranged from bright white to ominous gray with plenty of blue sun breaks for variety. This pair of images is terrific example of our good fortune.

Watching this F/A-18 Hornet approach us at near supersonic speed was particularly cool because of the vapor halo that kept forming around it. I always understood this to be the predictable result of an aircraft nearing the speed of sound. This turns out to be incorrect. The temperature and humidity have to be just right for the vapor cloud to appear.

National Geographic’s website explains it like this:

Despite its name, the sonic boom cloud doesn’t always come with a sonic boom, and it’s not a shock wave of the sound barrier being broken. The clouds only occur in unique weather conditions, when aircraft fly fast enough to cool the air around them, causing moisture in the air to condense into clouds. These halos of vapor appear for only a few seconds when aircraft reach speeds just below or just above the speed of sound (741 miles an hour/1,193 kilometers an hour).

This video footage shows the phenomenon occurring during one of the F/A-18′s flybys.

[Click on a thumbnail to view the entire image.]

©2011 Timothy Linn. All Rights Reserved.