17.2 Heating the Atmosphere
Heat The energy transfer from one object to another, due to a difference in temperature.
Temperature Average amount of Kinetic Energy (energy of motion) in a substance Measured with a thermometer Units: degrees (C or F)
Conduction: Direct Contact Heat Transfer Transfer of heat through molecules of a solid Energy always transfers from HOT → COLD Least important method of heat transfer in atmosphere.
Convection Transfer of heat through mass movement within a fluid (gas or liquid) Most heat in troposphere is moved by convection As fluid is heated it expands, becomes less dense than the fluid around it, and rises, while more dense fluid fills the space left behind.
Radiation Travels in all directions from its source. Unlike convection and conduction, radiation needs no material through which to travel Objects that are good absorbers of radiant heat are good at emitting radiant heat.
Energy from the Sun Energy travels to Earth as electromagnetic waves Electromagnetic waves can travel through empty space. Transfer of energy by electromagnetic waves is called radiation
All energy from the sun comes through Electromagnetic (EM) Waves Travels at 300,000 km/sec The EM Spectrum divides energy according to wavelength
Electromagnetic Waves Ultraviolet radiation has a higher frequency than visible light. Infrared has a lower frequency than visible light.
Visible Light A mixture of colors that you can see Colors are based on wavelength
Infrared Radiation Energy with wavelengths longer than visible light Ex: heat lamp for reptiles
Ultraviolet Radiation Energy with wavelengths shorter than visible light May cause sunburns/cancer (damages DNA)
Energy in the Atmosphere: Some is absorbed, some is reflected Greenhouse gases: CO2, CH4, H2O
Why is the sky blue? Scattering - reflection of light in all directions Gases scatter more blue light (short wavelength) This makes the sky appear blue
Why Sunsets Are Red.
The Greenhouse Effect Natural process in which gases hold heat in the atmosphere Infrared radiation is trapped by greenhouse gases Example: Methane, Water Vapor, Carbon Dioxide
Increases in CO2 in the atmosphere is causing an imbalance of the greenhouse effect, and rising temperatures of atmosphere and ocean.