climate:
the long term average weather conditions for a location calculated over 30 years.
what’s the difference between weather and climate?
climate is what you expect, weather is what you get
what is climate change:
the long term shift in an areas climatic condition
what influences the earths temperature
- insolation (varying, equatorial areas receive more insolation, whereas at the poles temp is lower)
- seasonal change (Southern Hemisphere summer, is tilted towards the sun)
where does precipitation occur?
- regions of rising moist air and low pressure
- highest in the tropics near the equator
- lowest in the poles as their is not enough moisture in the air
what natural systems drive the earths climate?
- the heat budget and greenhouse effect
- the hydrological cycle
- the carbon cycle
- atmospheric circulation
- ocean currents
what is the heat budget?
the driving force of all climate systems. all heat and insolation received by the earth must be returned to space otherwise the world would heat up endlessly.
what is the natural greenhouse effect?
- gases in the atmosphere (such as CO2, methane and water vapour) are essential in retaining heat to keep the planet warm enough to sustain life.
- this is done when gases in the atmosphere absorb terrestrial radiation coming from earths surface and re-radiate it in all directions. this is done in an attempt to slow the rate heat exits the atmosphere.
what happens to incoming solar radiation (6)
- 3% absorbed by clouds
- 16% absorbed by dust, vapour and CO2
- 51% absorbed by land and water
- 6% reflected by atmosphere
- 20% reflected by clouds
- 4% reflected by water and land
what happens to outgoing solar radiation?
- 21% re-radiated in long wave radiation
- 6% reflected from earths surface
- 21% reflected by clouds
- 20% reflected by latent heat
what are the 4 main processes in the hydrological cycle?
- Evaporation= the process of water changing from a liquid to a gaseous state
- condensation= the process of water changing from gaseous to liquid
- precipitation= occurs when rain, snow, hail falls from the sky
- transpiration=the process of water being evaporated from the pores of leaves and plants.
describe the process of evaporation;
as insolation from the sun heats large bodies of water, evaporation occurs as water molecules are released into the atmosphere
describe the process of condensation:
as water vapour rises, it becomes cooler, and its physical state changes to tiny water droplets
describe the process of precipitation;
when enough liquid has condensed, the atmosphere can’t support the weight, and gravity causes it to fall back to the earth.
how do the heat budget and hydrological cycle interact? (6)
- evaporation caused via heat energy from the heat budget
- this same heat energy is used in the process of transpiration
- warm ocean currents along equator caused via heat budget allow for more evaporation
- clouds formed via hydrological cycle, affecting heat budget via cloud-albedo effect (blocking of insolation)
- condensation releases latent heat energy stored from evaporation-this aids the heat budget in moving of heat from earth to space
- water vapour is a greenhouse gas therefor aiding in absorption and re-radiation of terrestrial radiation (helps maintain earths temp)
natural causes of climate change?
- external influences include; fluctuations in energy emitted by sun (sunspots), changes in orbit/axial tilt affecting distribution of solar energy.
- internal influences include; variations in composition of greenhouse gases, changes in surface reflectivity, plate tectonics and cooling effects of volcanic dust
anthropogenic causes of climate change?
- greenhouse gas emissions via burning of fossil fuels
- wet rice paddies release lots of methane
- livestock creates 29% of global methane emissions
- power generation
- transportation
how do sunspots work?
- sunspots work on an 11 year cycle, breaking very 5.5 years. huge magnetic storms occur on the suns surface that break the magnetic field, causing excess radiation.
- this excess radiation is released as coronal mass ejections or solar flares
explain how volcanic dust can cause climate change?
- when there is a volcanic eruption there is a brief period time of immense heating, however a period of cooling also follows.
- during an eruption, all the gases (sulphuric dioxide, co2), dust and ash in the atmosphere reflect insolation
- millions of tonnes of sulphur dioxide has the potential to reach the stratosphere (50km), where it then converts to reflective aerosol (sulphuric acid) over a period of months
explain how fossil fuels cause climate change?
- fossil fuels are burned in order to generate power (appliances, transport etc)
- fossil fuels contain carbon and when burned release co2, sulphur dioxide and nitrous oxide
- an increase of gases in our atmosphere slow the passage of terrestrial radiation back to space, due to atmosphere absorbing and re-emiting gg, these gases are sent in all directions-including back to earth resulting in a warmer surface for longer periods of time.
why is there less precipitation in the poles?
- due to a lack of evaporation (thus moisture in the air- less sun)
- when there are small amounts of moisture in the air, the cold air doesn’t allow it to rise and create clouds, any precipitation/ moisture freezes as ice.
- due to being in an area of high pressure, the descending air lacks moisture resulting in less cloud cover.
why is there lots of rainfall near the equator?
-strong solar heating creates uplift of moist air forming heat lows resulting in thunderstorms
describe mid-lattitude temperature regions precipitation patterns
- moderate with most of the precipitation created with cold fronts within sub polar or mid latitude low pressure systems
- form when moist air rises as cold polar air masses collide and wedge under the warmer air.
what is restoration?
the process and act of restoring land cover within the ecosystem back to its original state following human actions/involvement.
