Ch. 26.1 Factors That Affect Climate Chapter 26--Climate Ch. 26.1 Factors That Affect Climate

Climate—The weather patterns of a region that occur over many years. Most often described in terms of monthly and yearly temperature and precipitation. Temperature Range—the difference between the highest and lowest temperatures of a day or month. Locations with the same average temp. can have different temperature ranges.

Average yearly precipitation is also misleading…a location may receive regular precipitation, or it may experience wet and dry seasons. Factors used to describe climate also include latitude, heat absorption and release, and topography.

Latitude Solar energy received varies with latitude. Two factors—the angle that the sun’s rays strike the earth, and… The number of hours of daylight received by the area. Angle of rays depends on latitude and Earth’s tilt on its axis.

Near the equator, very direct rays, and about 12 hrs of daylight year round result in steady high temperatures. At higher latitudes, there are less direct rays, resulting in less heating. Daylight hours variations between summer and winter result in large temp. ranges. The most extreme yearly temp. ranges occur in the polar regions.

Global Wind Patterns Determined by latitude, and influence weather conditions such as precipitation, humidity, temperature, and cloud cover. Areas with different prevailing winds often have different climates. Review Ch. 23.3 pg. 469 – 472.

Heat Absorption and Release Solar energy striking the earth influences surface temperature. Land heats faster than water. Land heats to a higher temp. than water. The specific heat (amount of heat needed to increase the temp. of 1g of a substance 1 degree C) of water is higher than that of land. Water warms and releases heat more slowly than land.

Because evaporation is a cooling process, evaporation affects water surfaces much more than land surfaces.

Ocean Currents Amount of heat absorbed or released is influenced by ocean current temps. Direction of wind blowing over the ocean currents strongly affects climate. Westerly wind blowing across the warm Gulf Stream keeps NW Europe warmer than it would otherwise be.

Seasonal Winds Caused by heat differences between land and ocean. In summer, land heats up more quickly than the ocean water. Warm rising air over the land and the resulting low pressure causes cool, moist wind from the ocean to move onshore. In winter, the reverse occurs…these seasonal winds are called monsoons.

Topography Shape of land influences climate. Temp. decreases as altitude increases…O.7 degrees C per 100 m. Air rises and cools when it encounters mountains. It loses moisture through precipitation. On the downslope, the air compresses, dries, and warms. Foen winds in the Alps; Chinooks in the Rockies.

Downhill wind may remain cold despite heating, because they start out so cold…Mistral winds from the Alps to the Mediterranean, and Bora winds from Greece and the Balkan nations to the Adriatic Sea.