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Chapter 14. Climate. Defining Climate. Climate = long term weather patterns… Averages and variations in temp., precip., wind, etc. Normals: 30+ year averages of daily high and low temp, rainfall, wind speed and wind direction, measured at a specific location
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Chapter 14 Climate
Defining Climate • Climate = long term weather patterns… • Averages and variations in temp., precip., wind, etc. • Normals: • 30+ year averages of daily high and low temp, rainfall, wind speed and wind direction, measured at a specific location • Normals are not necessarily usual weather conditions
Factors that Influence Climate • Latitude (north or south of the equator) • Topography (rain shadow effect) • Air masses
Climate Classification • Köppen’s classification system—based on temperature, precipitation, and vegetation • Tropical (high temp. year round) • Dry—largest area (low precipitation) • Mild (warm summers, cool winters) • Continental (warm summers, cold winters) • Polar—also highlands (low temp. year round)
Microclimates • Microclimate—small localized climate • Heat Islands
Long-Term Climate Changes • Ice ages—currently we are in an interglacial period.
Short-Term Climate Changes • The reason for the seasons: axial tilt
Short-Term Climate Changes • El-Niño—changes in southern Pacific Ocean with global effects • Volcanoes tend to decrease global temperatures
Natural Causes of Climate Change • Solar/sunspot activity—11 year cycle • Maunder minimum: low sunspot activity from 1645 to 1716 corresponds to “Little Ice Age.” • Long-term changes in Earth’s orbit, tilt, and wobble cause cycles in temperature (ice ages)
Natural greenhouse effect • NOT related to the hole in the ozone layer!
Impact of Human Activities • Anthropogenic climate change (global warming) • Increase in carbon dioxide (CO2) in the atmosphere due to: • Burning fossil fuels • Deforestation