Chapter 14 Climate Defining Climate Climate long term

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 (CO 2) in the atmosphere due to: – Burning fossil fuels – Deforestation