atmosphere

  • the atmosphere → the gaseous envelope surrounding the Earth, mostly composed of oxygen and nitrogen; four layers: troposphere, stratosphere, mesosphere, thermosphere
    • temperature changes as you move through the atmosphere, different temperatures at different layers result in different reactions
    • 78% nitrogen, 21% oxygen, 0.93% argon, 0.04% CO2
  • troposphere → layer closest to the Earth, contains the most atmospheric mass, where weather occurs; average thickness of 12km
    • temperature decreases with increasing altitude (to -52℃)
  • stratosphere → contains the ozone layer, where planes fly; 11-50km above sea levels
    • temperature increases with increasing altitude (to -3℃) due to the absorption of UV radiation by the ozone
  • mesosphere → meteors; temperatures drop 50-80km above sea level
    • temperatures decrease to the lowest in the atmosphere (-138℃)
  • thermosphere → low atmospheric density, variable temperatures, auroras; 80-500km above sea level
    • temperatures vary but can be raised up to 1,000℃+
  • ecosystem services → processes that humans rely on (and often take for granted)
    • i.e. ozone layer blocks out harmful UV radiation and protects the earth, makes the earth warmer, provides oxygen, and allows visible light and some infrared to penetrate
    • oxygen balance
  • sun’s influence on Earth → The ultimate source of energy on Earth is the sun; based on the sun’s energy output and its distance from Earth, the global average temperature without the atmosphere would be -18℃ - however, in reality, it is about 15℃ (difference of 33℃)
  • planets ordered from warmest to coolest → Venus, Mercury, Earth, Mars
    • not because of the distance from the sun but due to the atmosphere - the atmosphere on Venus is very dense and traps a lot of heat, whereas Mars lost some of its atmosphere
  • solar radiation → electromagnetic radiation spectrum, includes gamma rays, x-rays, ultraviolet, visible light, infrared, microwave, and radio waves
    • high energy, short wavelength → gamma rays, x-rays, UV
    • low energy, long wavelength → infrared, radio waves
    • visible light passes through the atmosphere, UV light is absorbed by the ozone in the stratosphere, and infrared radiation (heat) is absorbed by CO2 and water in the troposphere
      • the stratosphere also absorbs gamma and X-rays
  • behaviours of EMR → when a wavelength of electromagnetic radiation moves out of the vacuum of space and enters the atmosphere, one of four things will happen
    • nothing (transmission); reflected by the earth and atmosphere (off of dust, clouds, etc); absorbed by water vapour, oxygen, ocean, land, etc; or absorption of high energy wavelength (re-emission of low energy wavelength and heat)
    • gases in the atmosphere act as a blanket, allowing visible light to penetrate and trap some of the infrared
  • substances that can absorb EMR → land masses, water (i.e. oceans), various gases in the atmosphere (O2, H2O, CO2)
  • earth-atmosphere energy balance → The atmosphere significantly contributes to the warming of the earth as it traps infrared radiation
    • 45 units of energy from the sun hit the earth and warm it, and 88 units of infrared energy are being reflected from the atmosphere
  • the sun and latitude → Because the Earth is round and slightly tilted on its axis, the sun doesn’t hit its surface evenly except for at the equator, which explains seasonality
    • tilt of the earth (axial tilt) explains seasonality (NOT distance)
    • the tilt of the Earth’s axis causes more heat to be absorbed near the equator and progressively less towards the poles (farther from the equator)
  • perihelion → the point in Earth’s orbit where it is closest to the sub, occurs in January
  • aphelion → the point in Earth’s orbit where it is farthest from the sun, occurs in July
  • the atmosphere controls how energy is moderated around the Earth, temperature differences drive continuous circulation that moderates surface temperature on the Earth
  • Hadley circulation → the cycle of air rising, being laterally transported, and falling again at low latitudes; disperse and transport air, energy, and precipitation around the Earth
    • red areas where is air rising are wet zones
    • blue areas where the air is falling are dry zones and deserts
  • Hadley cells → create predictable weather patterns
  • consequences of Hadley circulation → creates the major wind systems of the world (trade winds, westerlies, polar easterlies,), causes jet streams; creates differential pressure patterns; creates differential precipitation patterns; creates predictable weather patterns
  • atmospheric circulation → daily rotations (night and day) create te Coriolis effect
  • Coriolis effect → Earth’s rotation from west to east, moving air or water is deflected: right in the NH, left in the SH; influences wind direction
  • winds → small-scale horizontal movements, results of atmospheric pressure and Earth’s rotation
  • prevailing winds → major surface winds that blow continuously; polar easterlies, westerlies, and trade winds
  • polar vortex → a prevailing wind pattern that circles the Arctic around the Earth and normally keeps extremely cold air bottled up toward the north pole
    • when the vortex weakens it allows cold air to extend down across Canada into the U.S. or Eastern Europe
    • global warming weakens the polar easterly and warms up the Arctic quickly, causing ice to melt and expose more dark surfaces which in turn causes even faster warming as more energy is being retained
    • why cold temperatures can occur in southern regions as a result of global warming
  • oceanic conveyor belt/thermohaline circulation → the transfer of warm water from the Pacific Ocean to the Atlantic as a surface current; cold, dense water sinks and slowly flows from the Atlantic to the Pacific Ocean as a deep-water current
    • Circulation is determined by the temperature and the concentration of salt → the saltier it is, the denser the water
  • effects of ice melting → ice melting causes a large input of freshwater into the ocean, making the water colder and diluting the salinity, which can halt or slow down the thermohaline circulation
    • climate warming can generate colder winters due to the weakening of polar easterlies and the destruction of thermohaline circulation which reduces the power of the warm Gulf stream