338 Glossary
Primary energy Energy sources, such asfossil fuels, nuclear or wind power,
which are not used directly for energy but transformed into light, useful heat,
motor power and so on. For example, a coal-fired power station which
generates electricity uses coal as its primary energy
Proton A positively charged component of the atomic nucleus
PV Photovoltaic: a solar cell often made of silicon which convertssolar radiation
into electricity
Radiation budget The breakdown of the radiation which enters and leaves the
Earth’satmosphere. The quantity ofsolar radiationentering the atmosphere
from space on average is balanced by thethermal radiationleaving the Earth’s
surface and the atmosphere
Radiative forcing The change in average net radiation at the top of the
troposphere(the loweratmosphere) which occurs because of a change in the
concentration of agreenhouse gasor because of some other change in the
overall climate system. Cloud radiative forcing is the change in the net
radiation at the top of the troposphere due to the presence of the cloud
Reforestation Planting of forests on lands that have previously contained forests
but that have been converted to some other use
Renewable energy Energy sources which are not depleted by use, for example
hydro-power, PV solar cells, wind power andcoppicing
Respiration The series of chemical reactions by which plants and animals break
down stored foods with the use of oxygen to give energy,carbon dioxideand
water vapour
Sequestration Removal and storage, for example,carbon dioxidetaken from the
atmosphereinto plants viaphotosynthesis, or the storage of carbon dioxide in
old oil or gas wells
Sink Any process, activity or mechanism that removes a greenhouse gas, aerosol
or precursor of a greenhouse gas or aerosol from the atmosphere
Solar radiation Energy from the Sun
Sonde A device sent into theatmospherefor instance by balloon to obtain
information such as temperature andatmospheric pressure, and which sends
back information by radio
Stewardship The attitude that human beings should see the Earth as a garden to
be cultivated rather than a treasury to be raided. (See alsosustainable
development)
Stratosphere The region of the region of the atmosphere between about 10 and
50 km altitude where the temperature increases with height and where the
ozone layer is situated
Sustainable development Development which meets the needs of the present
without compromising the ability of future generations to meet their own needs
Thermal radiation Radiation emitted by all bodies, in amounts depending on
their temperature. Hot bodies emit more radiation than cold ones
Thermodynamics The First Law of thermodynamics expresses that in any
physical or chemical process energy is conserved (i.e. it is neither created or
destroyed). The Second Law of thermodynamics states that it is not possible to
construct a device which only takes heat energy from a reservoir and turns it