Transcript Chapter 26-

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.