Airborne Expedition to Yellowstone 1966

by E.X Berry and K.W. Nielsen, 1966

• Desert Research Institute
• Technical Report Series P
• Physical Sciences Publications No. 1
• Reno, Nevada, August 1966

In January 1966, four explorers flew the Desert Research Institute Beechcraft C-45 through Old Faithful Geyser and other geyser plumes in Yellowstone National Park, USA.

(After Ed received his PhD degree in 1965, DRI Director Wendell Mordy made him the manager of DRI’s Airborne Research Facility. That’s why we did a lot of stuff in the air. We learned stuff you don’t learn in books.)

We didn’t have go-pros or other digital cameras in those days. But we did have a time-lapse 16-mm camera in the nose of the Beech.

The movie film lay languished for 52 years until my son, Kim, recently put digitized versions of our time-lapse movies into this 12-minute video.

Here is our report (typed on a manual typewriter in 1966):

If you want a copy of our report, click on the download arrow.

Airborne Expedition to Yellowstone 1966

Prepared in Cooperation with the Bureau of Reclamation

Contract Number 14-06-D-5995

Acknowledgement

The authors gratefully acknowledge the talented aid of the other members of the crew: W. Carver, a graduate student in electrical engineering, who built and operated the airborne electronic system; and T. A. Wells, DRI’s all-weather pilot, who capably assured that this team’s story could later be told.

Wave clouds

This video shows our photos of wave clouds as we flew at 30,000 feet. The Beechcraft was not pressurized, so we used oxygen masks.

How did we get an old twin-engine Beechcraft C-45 to 30,000 feet, which was way above its rated altitude?

Answer: we flew the Beechcraft like a glider, staying in the updraft of the wave clouds to gain altitude.

When we were ready to come down, we flew out of the wave’s updraft and into its downdraft. That was like being in an elevator in freefall.

Water droplets and ice crystals

We found that water vapor condensed into water droplets and remained water droplets at temperatures much lower than zero degrees Celsius (0C). But at -26C, water droplets spontaneously turned into ice crystals. These droplets were less than 30 microns in diameter, or about the size of particles in cigarette smoke.

Sometimes, you see wave clouds over or downwind of mountains. Wave clouds are very smooth. They have a leading edge where the air rises and water vapor condenses into water droplets, and a trailing edge where the droplets or ice crystals evaporate.

Ice crystals last longer than water droplets, so ice crystals leave a much longer contrail than water droplets. Once water droplets become ice crystals, they will remain ice crystals unless they warm to 0C.

All engines that burn carbon fuels exhaust water vapor and carbon dioxide. The water vapor can condense into water droplets and form a contrail. If the air temperature is less than -26 C, the water droplets change to small ice crystals.

You can tell the difference between contrails or clouds composed of water droplets from those composed of ice crystals. Water droplet clouds have bright, shiny edges. Ice crystal clouds have hazy edges.