While doing some searching around for the next posting to Candid Conversations I came across an article on discoverynews.com. I was quite surprised to learn that certain types of aircraft, in the right conditions have the ability to affect how clouds react creating a change in weather and producing some interesting vistas in the skies above.
I contacted Andrew Heymsfield, the Principle Investigator during a study of this phenomenon and was delighted to get a reply. Andy thanks for being a part of Candid Conditions.
Cliff T.: What exactly do you do at the National Centre for Atmospheric Research and what was the study you were the PI for about?
Andrew Heymsfield: My field of interest is in ice microphysics, including the processes that lead to ice particle nucleation and growth, the effects of ice clouds on the earth's radiation budget, the representation of ice processes in models from weather forecast to climate scales, and the retrieval of ice cloud properties from ground-based and spaceborne remote sensors. I am a senior scientist and have worked at NCAR for 34 years. As for the experiment to study how ice particles initiate in clouds. The subject is difficult because “ice nuclei” are relatively few compared to cloud droplets and their measurement is difficult. Also, there are processes other than “nucleation” that can produce ice in subfreezing clouds. So, our goal was to study how ice was formed.
Cliff T.: Where was the study done?
Andrew Heymsfield: The project was based out of Metro Airport in Broomfield, CO.
Cliff T.: How was this done?
Andrew Heymsfield: We flew a plane through a cloud. On the day of our penetration of precipitation that formed, we flew a C-130 aircraft that produced a hole punch cloud, we took off with the goal of characterizing snow in a cloud layer situated between about 6000 and 12000 feet. We didn’t know it at the time but we flew right through the precipitation that was first detected by radar at about 15000 feet and then eventually grew and descended to the ground where it produced 2” of snow compared to none or a trace in the surrounding area.
Cliff T.: How does such an experiment help average people?
Andrew Heymsfield: By going back to the FAA aircraft tracks, we identified the two turboprop aircraft that produced the precipitation. Our interest, of course, is in explaining how Snow precipitation begins and develops, useful information for improving weather forecast models. After identifying the snow band generated by the aircraft, our goal was to figure out why and the broader implications. Although turboprop aircraft were suspected of producing such features, many of the early reports (1960’s-80’s) of hole punch clouds were from jet aircraft. We made the connection in the paper, explaining the process by which jet aircraft can produce hole punch clouds.
Cliff T.: From the way you describe what you have done Andy it sounds like this was not just work for you but, rather that you had fun doing this styudy. And, also by the fact that you have been doing your work for 34 years it is obvious that you have had a history of interest in weather. Thank you so very much for taking the time to write back and for sharing the story of this interesting study you did.
Andrew Heymsfield is a Senior Scientist with the National Centre for Atmospheric Research in Boulder Colorado. You can get the paper by following this link ftp://ftp.ucar.edu/pub/mmm/heyms1/hole_punch/
NASA Earth Observatory also has information on this topic.
