Strange Weather Sightings

The strangest weather I've ever seen....

On February 27, 1996 these clouds, called wave clouds were photographed by Ms. Loretta Jeffreys of Corl Street Elementary School in State College. Ms. Jeffreys' fifth grade class were taking their daily ten-minute centennial walk around the playground when they noticed this beautiful phenoma.

Excerpt of a letter written by fifth grader, Matt Kocher, describing the wave clouds seen during recess on February 27:

"... the clouds looked like thundering ocean waves. They kind of looked like a huge blanket falling down on us causing it to make large wrinkles. In some places it looked like there was a huge hole that could suck me right off the ground into the sky. The whole entire sky was filled with them. At some spots, they looked like upside down mountains."

Technically speaking lenticular or wave clouds are part of a forced phenomena, stationary disturbances around mountainous areas which produce these clouds. Wave clouds occur in stably stratified airstreams over irregular land masses which cause vertical oscillations about an equilibrium level. In other words, when stable air is displaced over a mountain, the air wants to return to its original position. This oscillations can last for tens of kilometers and extends in the direction of the wind.

Colloquially speaking, these clouds happen when stable air flows up over a mountain. When stable air flows over a moutain, it wants to return to its starting position or its equilibrium position. So when it does, the clouds produce a wavelike oscillation downstream through the atmosphere. The clouds pictured are stratus clouds and about 2000-4000 feet in the sky. These clouds bring rain or snow and depending on the wind direction, the intensity of the precipitation. The next few days had light snow and were windy.

The following diagram shows a profile of the temperature (right -blue line) and dewpoint (left - red line) that would be typical of an environment where wave clouds, like the ones seen above, would form. The bottom of the chart shows the pressure at the surface (ground level). Notice how the temperature and dewpoint lines converge (indicating saturation-cloud formation). These lines also bend to the right, showing a stable layer of air, where temperature is nearly steady with increasing altitude: