Transcript air
Review A- Albedo • • Is the % of solar radiation reflected by an object or surface Higher albedo = more radiation reflected by the surface • Albedo, together with reflection by the atmosphere, thus decreases the amount of incoming radiation that actually absorbed by Earth • High or low albedo? a. b. c. d. A mirror : ___________ A lawn : ___________ A sidewalk : ___________ An asphalt driveway : ____________ Albedo • • Is the % of solar radiation reflected by an object or surface Higher albedo = more radiation reflected by the surface • Albedo, together with reflection by the atmosphere, thus decreases the amount of incoming radiation that actually absorbed by Earth • High or low albedo? a. b. c. d. A mirror : high A lawn : low A sidewalk : low An asphalt driveway : low 8.8 Global Energy Transfer 8.8 Global Energy Transfer Intro • The equator receives more radiation than the poles Earth is not heated evenly. • Energy is transferred from equator to the poles • Water in the hydrosphere and air in the atmosphere act as heat sinks, storing a great deal of thermal energy • Comparing the same volumes, liquid water can hold more thermal energy than air How is energy transferred in the atmosphere? https://www.youtube.com/watch?v=WXuGYSM2D8k Atmospheric circulation • Air at equator heats up, moves up in the atm and becomes less dense creating areas of low pressure underneath (less matter) • Air cools and sinks towards the poles creating areas of high pressure •Air flows from high to low pressure creating wind. •Earth has permanent bands of high and low air pressure, thus there are prevailing winds that blow in the same direction almost all the time. •Due to Earth’s rotation, prevailing winds curve instead of moving directly north or south. They also push warm ocean water to the poles Energy transferred in the atmosphere • Convection currents: - a circular current in fluid (e.g. air, water) caused by rising of warm fluids as cold fluids sinks - Cold air holds less moisture and is drier than warm air https://www.youtube.com/watch?v=WXuGYSM2D8k •The Coriolis Effect •Air a the equator is rotating faster than air near the poles •Faster air moving towards the poles “gets ahead” of the surface and appears to shift eastwards (as viewed from space). •Slower air moving towards the equator (from poles) “lags behind” the rotating surface and appears to shift westwards (as view from space) https://www.youtube.com/watch?v=i2mec3vgeaI ENERGY TRANSFER IN OCEANS How prevailing winds influence climate? • Origin of prevailing winds (PW) influence whether climate is moist or dry • As PW pass over ocean, H2O vapour is picked up, When reaches land, it becomes rain • If PW come from poles, it’s cold and dry Oceans- the driving forces of climate and weather • https://www.youtube.com/watch?v=6vgvTeuoD WY How is energy transferred in the ocean? • Generally moves warm water from the equator to the poles and cold water from the poles to the equator • Ocean currents are driven by 1. surface winds (i.e. prevailing winds) 2. differences in salinity and temperature of ocean water. Demo • https://www.youtube.com/watch?v=4V5cOPK GEyE ( a more ideal version if we have the equipment) • https://www.youtube.com/watch?v=_Ww6BIy 3nc0 ( we did) 2. Ocean Current caused by different in density and temp. of water • Different seawater densities due to a. Cold water is denser than warm water b. Near the poles, ice is formed from fresh water leaving behind more salt in the remaining water (i.e. increasing sea water’s salinity) • Different seawater temperature: • Warm currents float while cold currents sink The Ocean Conveyor Belt Thermohaline circulation: the continuous flow of water around the world, driven by temperature and salinity differences https://www.youtube.com/watch?NR=1&v=SdgUyLTUYkg&feature=endscreens Examples of effects of Ocean currents • Brazil receives a warm ocean current making the climate warm and moist allowing rainforest to flourish • At the same latitude, Peru receives a cold ocean current, making the climate cool and dry (Atacama Desert in Peru) • http://oceanexplorer.noaa.gov/edu/learning/player/lesson 08.html