The greenhouse effect, in environmental science, is a popular term for the
effect that certain variable constituents of the Earth's lower atmosphere have on
surface temperatures. These gases--water vapor (H2O), carbon dioxide (CO2), and
methane (CH4)--keep ground temperatures at a global average of about 15 degrees
C (60 degrees F). Without them the average would be below the freezing point of
H20. The gases have this effect because as incoming solar radiation strikes the
surface, the surface gives off infrared radiation, or heat, that the gases trap and
keep near ground level. The e…
