Glossary of Terms

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

Arctic: The North Polar region.
Antarctic: The South Polar region.

B

C

Chapman reactions: So called after S. Chapman who is famous for his paper 'A theory of upper-atmosphere ozone, Mem. Roy. Meteorol. Soc.' in 1930 which set out the first theoretical explanation of the ozone layer in the stratosphere.
ChloroFluroCarbons (CFC's): A common industrial product, used in refrigeration systems, air conditioners, aerosols, solvents and in the production of some types of packaging. Although chemically inert in the lower atmosphere (troposphere), they are taken to very high altitudes where they are broken down into their components by the stronger sunlight (UV) at these altitudes. It is the chlorine formed in this process that causes the damage to ozone. The manufacture and use of CFCs in industry has been severely curtailed following the Montrol Protocol and subsequent amendments. See also halocarbons.

D

Dobson Unit: The unit of `Column (or Total) Ozone' - the amount of ozone directly above a point on the Earth's surface. More Information.

E

European Arctic Stratospheric Ozone Experiment (EASOE): A major European campaign, during winter 1991/92. More information. See also SESAME.
Exosphere: The layer of the atmosphere lying above 400 km altitude. More Information.

F

G

H

Halocarbons: A class of halide (i.e. containing Chlorine, Bromine or Iodine) compounds, including CFC's. These can break down to form various ozone-depleting radicals.

I

J

K

L

M

Mesosphere: The layer of the atmosphere lying between 50 - 100 km altitude. More Information.
Montreal Protocol: The crucial first step in limiting further damage to the ozone layer in the stratosphere. The Montreal Protocol was a convention signed in 1987 by many countries to greatly reduce the production and use of CFCs which had been shown to be responsible for damage to the ozone layer. Since 1987, further amendments to the protocol have imposed even greater restrictions of the production and use of potentially damaging compounds.

N

O

Ozone: A naturally occuring trace gas, chemical formula O3. In the stratosphere, it serves to absorb many harmful solar UV rays. More Information.

P

Polar Stratospheric Clouds (PSC's): The medium in which reservior chlorine comounds are converted into ozone-destroying chlorine radicals. They are clouds of ice/water particles, typically found at frost point in the stratosphere. More Information.
Polar Vortex: A distinct column of cold air contained over the poles (esp. South) by meterological effects. Develops during the polar winter when the polar regions are in polar night (sunlight does not reach the poles). Wind speeds around the vortex may reach 100 metres per second. The vortex establishes itself in the middle to lower stratosphere. It's important because it isolates the very cold air within it.
Potential Temperature: The temperature that a dry air parcel would have if transported adiabatically from its ambient temperature and pressure to a pressure of 1000 mb (millibars).
Potential Vorticity: The vorticity (curl of the wind field) that an air parcel would have if moved to a reference latitude and altitude. The entire dynamical behaviour of the atmosphere can be obtained from the knowledge of the entire PV field at all altitudes.

Q

R

Reservoir species: The reservoir species are those that hold ozone destroying chemicals in inactive forms. For example, HCl and ClONO₂, are reservoir species for chlorine. BrCl and BrONO₂ are reservoir species for bromine (Br). The reservoir species are important because their concentration tells us how many chlorine atoms are potentially available to destroy ozone in the perturbed chemical conditions of polar winters (see Part II: Chemical reactions leading to ozone loss for more details).

S

Second European Stratospheric Arctic and Mid-latitude Experiment (SESAME): A major European campaign, during 1994 and 1995. More information. See also EASOE.
Stratosphere: The layer of the atmosphere lying between 10 - 50 km altitude. More Information.

T

Thermosphere: The layer of the atmosphere lying between 100 - 400 km altitude. More information here.
THESEO: Third European Stratospheric Experiment on Ozone. See also SESAME and EASOE. THESEO runs from 1997-1999. More information can be found on the European Ozone Research Coordinating Unit website.
Tropopause: The narrow region separating the troposphere and the stratosphere. More information here..
Troposphere: The layer of the atmosphere lying below 10 km altitude. More information here.

U

V

W

X

Y

Z

© 1998. Centre for Atmospheric Science, Cambridge University, UK. No text or graphics can be used or reproduced without explicit written permission. This version designed and maintained by Dr. Glenn Carver. Original concept and design Owen Garrett.