Earth's Climate System
Atmosphere: A layer of gases that surrounds a planet or moon |
Climate: The characteristic pattern of weather conditions within a region, including temperature, wind velocity, precipitation, and other features, averaged over a long period of time |
The atmosphere regulates temperature on Earth |
Weather describes the condition of the atmosphere (wind, temperature, moisture) at a specific place at a specific time |
The Atmosphere and Climate
Greenhouse effect: The natural warming caused when gases in the Earth's atmosphere absorb thermal energy that is radiated by the Sun and Earth |
The greenhouse effect helps keep temperature fluctuations within a certain range |
| |
Winds |
Wind is the movement of air from an area of high pressure to an area of lower pressure |
Begins as a result of uneven heating on the Earth's surface |
The movement of wind affects ocean currents and therefore transfers thermal energy |
Winds blow in fairly constant directions called; these air currents are called prevailing winds |
When air masses interact, one air mass is usually pushed above the other → this air mass cools and condenses to form precipitation |
Jet streams are high altitude winds that travel long distances at high speeds → may carry warm, moist air and create precipitation or vise-versa |
Human Activity and Climate
Climate change is at least partially anthropogenic |
Anthropogenic: Relating to or resulting from the influence of humans |
The Industrial Revolution led to an increased use of fossil fuels |
The burning of fossil fuels leads to the release of gases and other pollutants which affect the greenhouse effect |
|
|
Earth and the Sun
Energy from the Sun is the most important factor that affects climate on Earth |
The intensity of the energy that reaches Earth affects the temperature of the air, water, and land → temperature produces winds, rains, and other features |
| |
Changes in Solar Activity |
Irregular fluctuations occur in the amount of radiation produced |
A sunspot cycle occurs every 11 years → these variations differ by 0.1% |
| |
Changes in Earth's Rotation, Orbit, and Tilt |
Throughout its orbit, Earth remains in the same orbital plane |
Earth's orbit, tilt, and rotation vary cyclically → these variations change the amount and location of solar radiation; produces changes in climate |
Eccentricity |
Earth's orbit cycles between circular and elliptical over a period of 100000 years |
Due to the gravitational influence of other planets |
There is less variation in the amount of radiation the Earth receives in a circular orbit than an elliptical one |
Affects the length and intensity of seasons |
Tilt |
Earth's axis of rotation is tilted about 23.5° from its orbital plane |
Angle of tilt varies by 2.4° between 22.1° and 24.5° over a period of 41000 years |
The greater the tilt, the greater the temperature difference between summer and winter |
Wobble |
Known as precession - varies cyclically over 26000 years |
Affects the amount and intensity of solar energy received by the northern and southern hemispheres at different times |
Latitude |
Climates differ due to the angle that the Sun's rays hit the Earth's surface |
The concentration of solar energy is greater at lower latitudes than higher ones |
|
|
The Hydrosphere and Climate
Hydrosphere: The collective mass of water found on, under, and over the surface of Earth in the form of liquid water, ice, and water vapour |
Water transfers heat around the planet |
| |
Oceans and Lakes |
Large bodies of water have a large specific heat capacity → the amount of heat required to raise the temperature of one gram of a substance by a degree celsius |
A large quantity of energy is needed to raise the temperature of water compared to land → the temperature of large bodies of water changes slowly and by smaller amounts |
| |
Ice and Snow |
Snow and ice reflect solar radiation due to their light colour → they have high albedo |
Albedo: The fraction of incident light or electromagnetic radiation that is reflected by the surface of an object |
Fresh snow can reflect 80%-90% of incident light |
The distribution of ice, water, and land greater affects the average global temperature |
Tectonic Plates and Climate
Earth's outer layer is composed of 12 major tectonic plates |
The changing distribution of land and water affects air and water circulations patterns and the transfer of thermal energy |
Tectonic plate: A piece of Earth's lithosphere that moves slowly on the asthenosphere |
The formation of mountains affect wind and precipitation patterns |
| |
Volcanic Eruptions |
Volcanic eruptions spew aerosols into the atmosphere |
Aerosols reflect solar radiation → have a cooling effect on the global climate |
May last from a few years to a decade; lasts until the particles are removed from the atmosphere by precipitation and settling |
Some types of volcanic eruptions may release greenhouse gases |
|
