1. Earth’s Climate System

2. Factors Affecting Climate Change  Earth is surrounded by a layer of gases called the atmosphere.  The characteristic pattern of weather conditions within a region averaged over a period of time is called the climate.  Climates around the world have changed many times over the billions of years of Earth’s history.  Earth is surrounded by a layer of gases called the atmosphere.  The characteristic pattern of weather conditions within a region averaged over a period of time is called the climate.  Climates around the world have changed many times over the billions of years of Earth’s history.

3. Earth and the Sun Energy from the Sun is the most important factor that affects climate on Earth Solar energy travels through space and hits Earth. The heat makes winds, rain and other features of weather. The solar radiation changes: a sunspot cycle occurs every 11 years, perhaps the cause of climate change in the past?

4. Changes in Earth’s Rotation, Orbit and Tilt Eccentricity: Earth’s orbit fluctuates slightly every 100 000 years. It’s path goes from circular to elliptical, and back again. This affects the length of seasons Tilt: changes over 41 000 years about 2.4 . Currently we are at 23.44 , which is at the midpoint of the range of change. Wobble: Earth is not a perfect sphere, so it wobbles a bit on its axis as it rotates

5. Latitude on Climate Climate is hotter at the equator due to the angle at which the Sun’s rays hit Earth, not how close we are to the Sun.

6. Atmosphere and Climate  Made of mainly nitrogen, oxygen and water vapour.  Greenhouse Effect: natural warming caused when gases in Earth’s atmosphere absorb thermal energy from Sun and Earth.  Without it, Earth would radiate it’s energy back into space and it would be a lot colder on Earth.  Made of mainly nitrogen, oxygen and water vapour.  Greenhouse Effect: natural warming caused when gases in Earth’s atmosphere absorb thermal energy from Sun and Earth.  Without it, Earth would radiate it’s energy back into space and it would be a lot colder on Earth.

7. Winds  Wind is the movement of air from an area of high pressure to an area of low pressure.  Wind starts as an uneven heating of the Earth’s surface.  This in turn affects precipitation and ocean currents.  Wind is the movement of air from an area of high pressure to an area of low pressure.  Wind starts as an uneven heating of the Earth’s surface.  This in turn affects precipitation and ocean currents.

8. Winds and Ocean Currents  Energy from the moving air is transferred to the surface of the water, causing the water to move.  Winds blow in fairly constant directions around the Earth’s surface, called prevailing winds.  Energy from the moving air is transferred to the surface of the water, causing the water to move.  Winds blow in fairly constant directions around the Earth’s surface, called prevailing winds.

10. Winds Affect Precipitation  When air masses meet, usually one moves over the other.  The rising air cools, and any water vapour in the air condenses to form precipitation.  Jet streams are high-altitude that travel long distances at high speeds.  When air masses meet, usually one moves over the other.  The rising air cools, and any water vapour in the air condenses to form precipitation.  Jet streams are high-altitude that travel long distances at high speeds.

11. Hydrosphere  Invisible water vapour and clouds of water droplets drift through the atmosphere.  All the water in its different forms on Earth composes the hydrosphere.  Oceans and lakes act as heat reservoirs because they can hold more heat than the atmosphere can.  Water has a large specific heat capacity (takes a lot of energy to raise the temperature of water)  The albedo is the amount of incident light that is reflected by the surface of an object.  Invisible water vapour and clouds of water droplets drift through the atmosphere.  All the water in its different forms on Earth composes the hydrosphere.  Oceans and lakes act as heat reservoirs because they can hold more heat than the atmosphere can.  Water has a large specific heat capacity (takes a lot of energy to raise the temperature of water)  The albedo is the amount of incident light that is reflected by the surface of an object.

12. Tectonic Plates  Earth’s outer layer is made of tectonic plates  They move around on the slowly flowing rock layer.  Earth has about 12 plates  Move a few cm each year  Shapes of oceans and continents are always changing.  Earth’s outer layer is made of tectonic plates  They move around on the slowly flowing rock layer.  Earth has about 12 plates  Move a few cm each year  Shapes of oceans and continents are always changing.

13. Volcanic Eruptions  Movement of plates produce volcanic eruptions  Volcanoes are usually located at boundaries of plates.  Ash causes solar radiation to reflect and can have a cooling effect on the global climate.  Some other types of eruptions may raise global temperatures due to emitting greenhouse gases.  Movement of plates produce volcanic eruptions  Volcanoes are usually located at boundaries of plates.  Ash causes solar radiation to reflect and can have a cooling effect on the global climate.  Some other types of eruptions may raise global temperatures due to emitting greenhouse gases.

14. Human Activity  None of the previously mentioned factors can explain the warming trend we are experiencing now.  There is growing evidence that the present change in climate is at least partly due to anthropogenic causes. (caused by humans)  Due to burning fossil fuels (cars, factories, farming, home, electricity, etc) we are creating huge amounts of greenhouse gases.  None of the previously mentioned factors can explain the warming trend we are experiencing now.  There is growing evidence that the present change in climate is at least partly due to anthropogenic causes. (caused by humans)  Due to burning fossil fuels (cars, factories, farming, home, electricity, etc) we are creating huge amounts of greenhouse gases.