Energy Transfer in the Climate System

What is a system? A group of interdependent parts that work together to form a single functioning whole. (e.g. digestive system) There are 2 types of systems: 1. open system 2. closed system

Two types of systems: In an open system, energy and matter cross the system’s boundary. (e.g. humans intake food, H2O, O2, & release CO2, H20 vapour, waste, & thermal energy). In a closed system, energy only crosses the system’s boundary. (e.g. Earth is a closed system. Matter stays within the planets boundaries.)

Feedback Loops Process in which part of a system’s output is returned, or fed back, to the input. There are 2 types of feedback loops: 1. Positive feedback loops 2. Negative feedback loops

Positive Feedback Loop Acts to increase the effects of the interacting parts, leading to larger and larger changes.

Negative Feedback Loop Decreases the effects of the interacting parts and helps to maintain a system’s equilibrium. E.g. (p.313 Fig. 8.3) Global warming -> increases temperatures -> increase evaporation -> increase cloud cover -> increase albedo -> decreases global warming

Electromagnetic Radiation Is Energy that travels as waves that move outward in all directions from a source. E.g. infrared radiation, ultraviolet radiation, radio waves, X-rays, gamma rays, and visible light.

Types of Energy Transfer Radiation Transfer of thermal energy / heat as electromagnetic radiation Conduction Transfer of thermal energy from hot to cold surface Convection Transfer of energy by highly energized molecules moving from one place to another (in liquids and gases only)

Radiation, Conduction & Convection

Energy Transfer in the Atmosphere (See p. 315, Fig. 8.4)

Principles of Ocean Water Cold water is more dense, so it sinks to the ocean floor pushing warmer water out of the way Salt water is more dense that freshwater, so salt water sinks.

Energy Transfer in the Ocean (See p. 316 Fig. 8.5) Thermohaline Circulation: “The great ocean conveyor belt” The relationship between temperature, salinity (salt levels), and density of water create a continuous, twisting ocean current that mixes ocean water from North America to South Pacific. Distributes global thermal energy Promotes upwelling (upward vertical motion of ocean current which brings nutrients from floor to surface for marine animals).

Effects on Global Warming on Thermohaline Global Warming=increase ice melting=increase freshwater in northern oceans=less salinity (less dense water) Global warming=increase evaporation in tropical waters (more dense water)

Effects on Global Warming on Thermohaline Conclusion: polar water is less likely to sink toward the ocean floor, this affects thermal energy transfer between oceans & atmosphere. Decrease in upwelling = decrease in nutrients for marine life http://www.youtube.com/watch?v=MZbsMlr9WRI&NR=1 http://www.youtube.com/watch?v=Q_yXHGQYpBc

El Nino & La Nina National Geographic insert P. 318-319

Normal Pacific Tradewinds Normal trade winds near equator blow to the west. Thus: warm surface water piles up in west Pacific cold nutrient-rich water wells up in the east Pacific. Rainfall in west Pacific

El Niño El Niño occurs when trade winds are slackened or reverse warm surface waters from western Pacific move East & jet streams carry warm moist air to parts of North America Prevents nutrient upwelling = marine animals suffer (lack of food) East Pacific gets a lot of rain. & increases temperatures across North America Worldwide climatic ramifications

El Niño Year http://www.youtube.com/watch?v=fN_NmCpry38

La Niña -Stronger than normal westward winds push warm Pacific waters farther west to Asia -Cold deep sea waters then build up strongly in Eastern Pacific bringing cooler temperatures to northwest North America, & hot dry weather to southern areas

La Nina Year http://www.youtube.com/watch?v=U7lw2RsxhEs

Earth’s Energy Budget Description of total energy exchange within a system. Summary of how energy from the Sun enters, moves through, and leaves the Earth system.

Earth’s Temperature Today: The Earth’s temperature has been relatively stable over the past millions of years. To maintain this, incoming energy must equal outgoing energy. Our energy budget is changing: Reflection of Solar Radiation= 30% Absorption of Solar Radiation = 70%

Earth’s Albedo

Work: P. 314 #1-4 P. 317 #5-8 P. 322 #1-8