The Global Environment - Unit 2 (Atmosphere)

Perihelion

Closest to the sun, Northern Hemisphere: July 4

Aphelion

Closest to the sun, Northern Hemisphere: Jan 3

Radiation

Form of energy transfer that does require mass or direct contact between bodies

Short wavelengths

Higher frequency, higher energy (Gamma rays, x-rays, ultra-violet)

Longer wavelengths

Lower frequency, lower energy (Infrared, radio waves)

Temperature

Average measure of kinetic energy/speed of molecular movement

Heat

Transfer of energy from one body to another, always flows from high to low, stops when temperature equalizes

Hot objects

More energy, shorter wavelengths

Cold objects

Less energy, longer wavelength

Blackbody phenomena

Perfect emitters and absorbers of radiation at all wavelengths (ex: the sun)

Shortwave radiation

From the sun

Longwave radiation

Earth’s emission into space

Law of Conservation

Energy cannot be created or destroyed, only transferred or converted

Entropy

Conversion to heat is the ultimate fate of energy, heat is transferred from objects/regions with high temperature to those with low temperature

Net Radiation

The balance between incoming/outgoing energy

Latitudinal imbalances

Variation, uneven distribution in solar energy based on geometry, function of latitude

Net Radiation: higher latitudes

Negative net radiation

Net Radiation: tropic zones

Largest positive net radiation

Net Radiation: Antarctica

Lowest net radiation (albedo)

Insolation

Solar energy that is incoming to Earth systems

Solar Declination

The latitude that receives direct overhead insolation on a particular day

Subsolar point

The only point receiving perpendicular insolation at a given moment (the sun is directly overhead), migrates annually between Tropic of Cancer and Tropic of Capricorn

Reasons for seasons

Revolution (orbit around the sun), rotation (Earth turning on its axis), tilt, axial parallelism (fixed axial alignment throughout the year), sphericity

Seasonality

Fluctuations most active/present in mid-latitude regions, “expected” variability, cascading effects when thing change

Changing climate and season fluctuations

Effects timing of seasonal events (migrations, budding, etc.), duration of seasonal events (wildfires, hurricanes, etc.), variability of events (“Tornado Alley” location)

Photon

“Massless particles",” stable, no electron charge

UV-A

“Longwave UV” or “BlackLight,” 95% of solar radiation we receive from the sun, responsible for signs of aging, absorbs deep into skin tissue (suntan)

UV-B

Medium wave UV, ~5% of all solar radiation, damages skin tissue (sunburn), some absorbed by earth’s atmosphere

UV-C

Shorter wave UV, mostly trapped by earth’s atmosphere, anti-pathogen uses, mostly absorbed by the earth’s atmosphere

Ionizing radiation

UV-C, acute (treat cancers), chronic (cause cancers)

Ozonosphere

O3, naturally exists as a concentrated layer in the stratosphere, filters UV radiation entering Earth’s atmosphere

UV Index

1 to 11+ risk scale for sun exposure, 0=no risk (nighttime), determined by level of ozone present, sun angle, and cloud cover

Ionosphere

Upper earth atmosphere, contains: exosphere, thermosphere, and mesosphere, influences radio and GPS signals, outer functional layer

Exosphere

Protective layer, made up of hydrogen and helium atoms, highly variable temperature

Thermosphere

Where UV absorption occurs, location of International Space Station, larger portion of the ionosphere

Magnetosphere

Charged particles captured and held within a planet’s atmosphere, deflects potential damages

Middle Atmosphere

Mesosphere, stratosphere, “near space”

Mesosphere

Coldest region of the atmosphere, temperature decreases as altitude increases (function of solar radiation and infrared heat trapped within)

Stratosphere

Enables oxygen exchange need for biological life, temperature stratified (warmer layers in upper atmosphere, cooler layers closer to Earth)

Troposphere

Where weather occurs and planes fly, temperature decreases with altitude, greatest variation in mid-latitudes

Earth’s Atmosphere

Veil of gases surrounding Earth, produce a protective boundary between outer space and the biosphere

Air pressure

Molecular activity, force exerted from colliding gas molecules on all surfaces

Atmospheric pressure

Pressure exerted by the weight of air present

Upper atmosphere

Less dense, fewer collisions, less pressure

Lower atmosphere

Denser, more collisions, more pressure

Altitude and Air Pressure

“Thinning” air in upper attitudes

Heterosphere

Not uniform, outer atmosphere, gases not evenly mixed/distributed, layers defined by atomic weight (constant gases)

Homosphere

Uniform, gases more evenly blended, exception of the ozone layer, mix of materials (variable gases)

Constant gases

Nitrogen, oxygen, argon

Variable gases

Absorb/transmit radiant energy (water vapor, carbon dioxide, greenhouse gases), influence global temperatures

Water vapor

Earth’s most abundant variable gas, function of latitude and landforms: highest in tropical zones, lowest over deserts and dry, high latitudes

Thermopause

Outermost layer, temperature extremes

Environmental Lapse Rate

Rate of temperature decreases with altitude increase

CFCs (chlorofluorocarbons)

Aerosol propellants, fire suppressants, refrigerants. UV radiation splits CFCs, releasing chlorine that breaks down ozone molecules

Montreal Protocol

International agreement to restore the ozone layer, CFC banned

Natural factors impacting air quality

Wind direction and speed (dust transmission), local landscapes, volcanic activity (enhanced conditions (vog)), temperature inversions

Temperature inversion

Layer of warmer air overlies cooler air (rather than temperature decreases as altitude increases), results in a layer that traps pollutants

Air Quality Index (EPA)

Generalized risk exposure: 0-500, determined by carbon monoxide, nitrogen dioxide, sulfur dioxide, ground-level ozone, and particulate matter

Earth’s Radiation “Budget”

Based on law of conservation of energy, balance between incoming solar radiation and outgoing radiation, budget “out of balance” can affect temperature and climate

Energy Balance

Inputs: insolation (shortwave), Outputs: radiation back to space (longwave)

Scattering Radiation

Insolation/photons collide with higher concentrations of molecules as they reach Earth, interactions redirect light

Diffuse Radiation

Redirected energy waves, “shadowless light,” weaker, dispersed radiation is traveling in different directions

Rayleigh Scattering

Particles are smaller than the wavelength of light moving through, makes the sky blue

Mie Scattering

Atmospheric particles larger than wavelengths of light, produces white clouds, smog/haze

Refraction

Bending light waves, function of angles, temperature, air quality

Albedo

Reflective quality, intrinsic brightness

Direct Radiation

~50% of all insolation received by the outer atmosphere makes it to the Earth surface (rest is back radiation)

Transmission

Uninterrupted passage of short and long wave energy as direct radiation (through the atmosphere and water)

Absorption

Radiation that is converted into other energy (photosynthesis, longwave radiation (infrared heat)), produced heat energy

Heat

Flow of kinetic energy between molecules, from one substance to another, function of temperature difference (higher to lower)

Sensible Heat

“Sensed” by humans as temperature, function of kinetic energy

Latent Heat

“Hidden” heat energy, surrounding material experiences gains/losses, but not the substance itself; lost/gained during changes in state of matter

Specific Heat

The capacity for a substance to absorb heat and change temperature, how much energy is necessary to change the temperature/state of matter (water has a higher specific heat than land)

Conduction

Molecule-to-molecule transfer of energy (gas to liquid/solid)

Convection

Mixing, circulation as a means of transfer (warmer masses rise, cooler masses sink)

Greenhouse analogy

Earth’s atmosphere, as a result of greenhouse gases, trap and delay outgoing radiation back into space, warming the surface and lower atmosphere

Greenhouse gases

Shortwave radiation absorbers

Clouds in the atmosphere

Influence heating and cooling conditions, reflect incoming short and longwave radiation

Cloud forcing

Thick clouds: reflects insolation, cooling effect if exceeds greenhouse effects. Greenhouse: reflects only 50% of insolation, warming effect when greenhouse effect exceeds

Advection

Horizontal convection motion (wind)

Diurnal Cycles

Daily patterns, varies with season and latitude

Lag time

Heat loss in atmospheric gases, both daily (after 12pm) and annually

Net Radiation: Latent heat

Energy released in a change from liquid to gas, highest in tropics and diffuses toward poles (hot, dry air meets warm ocean water)

Net Radiation: Sensible heat

Land-air heat exchange via convection and conduction, highest in subtropical latitudes (hot, dry air, waterless surfaces, cloudless skies, little vegetation)

Ground heat

Conductivity in and out of land or water, snow melt (can include ambient heat)

Microclimates

Function of latitude and elevation (why mountains have a snowline)

Cold snap

Dramatic drop in temperature over a 24 hr. period, location dependent

Heat wave

Prolonged, abnormally high temperatures, amplified by humidity, can trigger other events (wildfires)

Rising global temperatures

Influenced by delayed back radiation and urbanization

Urban Heat Island Effect

Temperature differences from suburban to rural areas, influenced by lack of shade and albedo