Ask A Scientist
If hot air rises, why are mountaintops covered with snow?
Asked by: Elizabeth DoBell
School: African Road Elementary School
Teacher: Miss Weisbrod
Hobbies/Interests: I like science and gymnastics
Career Interest: Teacher
Answer from George Catalano
Professor of Mechanical Engineering, Director of t
Turbulence, Fluid Mechanics, Aerodynamics, Environmental Ethics, and Modeling Ecosystems
University of Virginia, Aerospace Engineering, 1977
All things Italian, Creative Arts, Model trains & cars
Wife, Karen, is a registered yoga teacher at Yoga for Everybody at the Orthopedic Associates; lives with 3 Alaskan Malamutes, two more in our hearts
Have you ever seen any of those old barnstormer type airplanes (biplanes) at the Binghamton air show? The cockpits are open and just as in the cartoon strips of Snoopy and the Red Baron, it is pretty cold up there. Pilots including Snoopy have to wear warm mufflers and gloves. So the Earth's atmosphere becomes cooler and cooler as you reach higher and higher altitudes-at least until you get to the stratosphere. Lucky for Snoopy, biplanes never quite get that high! As air particles rise, the air around them gets colder and colder and eventually those molecules lose their excess heat and have the same temperature as the molecules that surround them. When the temperatures are the same, the densities or weights are the same, and the motions stops. So, hot air does rise for a while until it is cooled off by its surroundings. Let's get back to the mountains. The air at the top of mountains is often quite cold. The temperature at the summit of our state's beautiful Whiteface Mountain is presently -15 degrees Fahrenheit. That sounds pretty cold to me. So the mountains are safe from all the hot air that we generate down here at sea level. They are safe unless we change the nature of our Earth's atmosphere through the introduction of pollutants and a different balance of gases including more carbon dioxide. In that case, the Earth's atmosphere will begin to retain more heat and the process of global warming will have begun. Have you ever heard of coal miners using canaries to alert them to problems with the air in mine shafts? In a similar way, we can use the snow cover of mountain peaks as a warning device to alert us to changes in the Earth's atmosphere. Check out the snow pack covering Mt. Kilimanjaro today compared to ten or twenty years ago. You might be surprised at what you find out.