which accurately pinpoint global ocean heights quickly and more efficiently. For
example, from 1994 to 2004, scientists mathematically constructed graphs from satel-
lite altimeter measurements, showing that the global mean sea levels have risen any-
where between 1.10 and 1.18 inches (2.8 and 3.0 millimeters).
No matter what the method, scientists do know the global mean sea levels are
slowly rising. Many believe that about one quarter of the rise is caused by thermal
expansion as the oceans warm, and another one quarter by small glaciers melting
around the world. Some rise may also be caused by such human activities as burning
trees, pumping ground water, and draining wetlands. Currently, scientists are not
quite certain about the true rate of sea level rise, mainly because of the intensity of
working on the data: Ocean-tide gauge records must be averaged, over many decades,
and corrected for variable ocean dynamics and distortions of Earth’s crust.MATH IN METEOROLOGY
What is meteorology?
Meteorology is the study of atmospheric phenomena, their interactions, and process-
es. It is often considered part of the Earth sciences and is most commonly associated
with weather and weather forecasting.What is the compositionof the air?
Meteorologists determine the composition of air by analyzing its various constituents;
these are mainly displayed in terms of percent of the atmosphere. The first 40 to 50
miles (64 to 80 kilometers) above the surface contains 99 percent of the total mass of
the Earth’s atmosphere. It is generally uniform in composition, except for a high con-
centration of ozone, known as the ozone layer, at 12 to 30 miles (19 to 50 kilometers)
in altitude.
In the lowest part of the atmosphere—the area in which humans, other animals,
and plants live—the most common gases are nitrogen (78.09 percent), oxygen (20.95
percent), argon (0.93 percent), carbon dioxide (0.03 percent), and minute traces of
such gases as neon, helium, methane, krypton, hydrogen, xenon, and ozone. Water
vapor is also present in the lower atmosphere, although variable and at a very low per-
cent. Higher in the atmosphere, the composition and percentages change as the
atmosphere thins. (For more about percents, see “Math Basics.”)How is air temperature measured?
Simply put, there are two ways to look at air temperature: On the micro-scale, it is the
small scale measure of gas molecules’ average kinetic energy; on a larger scale, it is
304 the action of the atmospheric gases as a whole. In physics, an entire branch is devoted