Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne CFC's Reaching Stratosphere 
Name: María
Status: student
Age: 17
Location: N/A
Country: N/A
Date: 7/14/2004
Question:
Why do CFC's reach the stratosphere if they are heavier than the air?

Replies:
Maria,

CFCs in the atmosphere exist as gases. Gases have rather weak intermolecular attractions and they exhibit the property of diffusion -- that is, their molecules are in incessant vibrational, rotational, and translational motion. Even though their densities are greater than that of air, CFCs will ultimately mix with and diffuse about in air. In time, some will reach the uppermost parts of earth's atmosphere.

Regards,

ProfHoff 866

Gases, heavier than air, reach high altitudes by convection -- the physical mixing of masses of the atmosphere. Once there CFC's undergo photochemical chain reactions so that a small quantity of CFC's propagate atmosphere-damaging chemical reactions.

Vince Calder

Maria,

Almost any molecule or particle that is not too much heavier than air can be transported long distances horizontally or to great heights vertically by atmospheric motions. For instance, consider the great heights to which thunderstorms can reach, well into the stratosphere. As the air rises in the thunderstorm, it carries with it whatever pollution and particles that were near the surface. Thus they can end up in the stratosphere. Not being too much heavier than air and with little for mechanisms to remove them (little vertical motion, little water vapor, no precipitation, etc.), CFCs can reside in the stratosphere for a long time before they literally fall out down towards the Earth.

David R. Cook
Atmospheric Research Section
Environmental Research Division
Argonne National Laboratory

Click here to return to the Weather Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory