Climate Change

Atmosphere: The layer of gases that surround the Earth and form a protective layer against the sun’s radiation.

Weather Climate The condition of the atmosphere in a specific place at a specific time. The average conditions of the atmosphere over a period of time, over a large region. (ex. hot, cold, wet, dry, windy, etc.)

Factors That Affect Climate Change Earth and Sun Factors Atmospheric Factors Hydrospheric Factors Movement of Continents Human Factors

Earth and Sun Factors 1. Solar Activity: Single most important factor. The amount of solar energy that reaches earth varies with solar activity. When the number of sun spots is high, the sun emits more radiation. It has an 11 year cycle from minimum to maximum.

Earth and Sun Factors 2. Movement of Earth Eccentricity – earth’s orbit around the sun fluctuates from circular to oval. The closer the orbit, the more solar radiation reaches the earth. Cycle is 100 000 years- presently orbit is near circular.

Earth and Sun Factors Tilt – Earth rotates on an angle that varies from approx. 22o to 24o. The greater the tilt the greater the temperature differences b/w the seasons. Cycle is 41000 years- currently at 23o and decreasing. Precession (wobble) – because earth is not a perfect sphere, it wobbles slightly as it rotates. Cycle is 26000 years.

Earth and Sun Factors 3. Latitude Sun’s rays hit the earth more directly at the equator than at higher latitudes. At higher latitudes the rays are more dispersed resulting in less radiation.

Atmospheric Factors The Greenhouse Effect The atmosphere absorbs energy radiated by the sun and the earth. This helps to moderate earth’s temperature.

Atmospheric Factors 2. Winds The movement of air from an area of high pressure to low pressure. This movement transfers thermal energy around the world. Winds rotate clockwise in the north and counter clockwise in the south.

Atmospheric Factors Ocean Currents: Winds move ocean currents. Energy is transferred from air to water and is distributed around the globe. The air currents are called prevailing winds.

Hydrospheric Factors Hydrosphere: all the water in its different forms found on earth. Oceans & lakes act as heat reservoirs. Can hold much more heat than air because water has a higher specific heat capacity Defined as the amount of heat required to raise the temp of 1 g. of a substance 1 degree C.

Hydrospheric Factors Albedo Effect: The fraction of solar energy reflected by a surface. Depends largely on colour of the surface. Light colours reflect more energy and therefore have a higher albedo.

Movement of Continents Tectonic Plates: 12 major plates make up outer layer of earth’s crust. Constantly moving by tiny amounts each year. Affects transfer of energy b/w land and water.

Movement of Continents Volcanic Activity: Spew gases, ash and particles called aerosols into the atmosphere. This particulate matter reflects solar radiation and has a cooling effect on global climate.

Human Factors “Anthropogenic” – caused by humans. Burning of fossil fuels since the Industrial Revolution (1700’s). When burned release gases and pollutants into the atmosphere contributing to the greenhouse effect.