Earth's Systems and Resources - Environmental Science - page 17

Weather and Climate
Weather is the name given to the short-term events of temperature, wind, and precipitation. The constant pat-
terns developed from averaging the daily weather for an extended period of time is climate. Climate is typic-
ally the weather averages for at least 30 years. Many areas have recorded data for more than 100 years now,
though the more recent data is more accurate as instruments have become more standardized and computer-
ized.
The transfer of heat energy causes weather, and the source of heat energy is solar energy heating the Earth.
This solar energy heats the Earth unevenly because of the distribution of water and land on the Earth and the
specific heat of each. This heating of the Earth is reflected in the temperature, movement of air masses, and
availability of sunshine. The rotation of the Earth also plays a role in the weather patterns.
Latitude and altitude have an effect on the climate of a region. The farther from the equator, the less solar ra-
diation and the cooler the climate. There is also a greater seasonal variation throughout the year when farther
from the equator. Altitude, the distance above the Earth's surface (sea level), is also a determining factor on the
climate of a region. Each 1,000-foot gain in altitude reflects a 4°F decline in air temperature. For example, at
10,000 feet, an alpine tundra climate zone air temperature might average 35°F. Changes in latitude and altitude
influence plant and animal distribution.
Atmospheric Circulations
The circulation of air in the atmosphere is the result of solar heating, the rotation of the Earth, and the proper-
ties of air, land, and water. Earth is heated unevenly for three reasons:
• More solar energy hits the Earth at the equator than the poles , and the per unit of energy by per
surface square area varies.