Atmosphere Flashcards
Atmosphere
the gaseous envelope that surrounds a celestial body
The atmosphere is comprised of
a mixture of gases and suspended particles (liquid droplets called aerosols)
Haden Earth’s atmosphere
Primordial atmosphere - comprised of hydrogen, helium, methane, ammonia, and water with little winds that were stripped away from solar winds.
Second haden atmosphere
A primordial environment with little to no free oxygen, with proportions of water, CH4H2, nitrogen, carbon dioxide, and argon.
Archean to Proterozoic
- initial traces of O2, may have been formed by ultraviolet light breaking down water
- photosynthesis by cyanobacteria oxygenated atmosphere
Cyanobacteria oxygenated atmosphere between
2.5 and 1.8 billion years ago
Cyanobacteria transition is marked by
banded iron formations (alternating reduced and oxidized iron)
Cyanobacteria effect on ozone
with more O2 came ozone, which absorbed harmful UV radiation, making it possible for life to survive in shallow water and on land.
O2 comprises how much of today’s atmosphere
21%
Primary factors measured when studying the atmosphere include:
pressure, temperature, and moisture
Radio-stands
instruments that are used to measure altitude, pressure, temperature, relative humidity, wind speed, and wind direction
Barometers
Measure pressure, including mercury and aneroid barometers
Pressure Variation in the atmosphere
The pressure in the atmosphere decreases as you go up due to gases being highly compressible. Molecules are forced together by the mass of air above.
Isobars
Contours of constant air pressure
Air flows from regions of ____ pressure to ____ pressure. This drives ____ and ____.
High to low, drives winds and weather
Temperature
A measure of the average kinetic energy of molecules
Heat
the total kinetic energy of all molecules in a substance
Layers of Atmosphere
Troposphere, stratosphere, mesosphere, and thermosphere
Troposphere thickness
16-10 km thick from the equator
How is the troposphere heated
through energy transfer from earth’s surface with the base of the troposphere being the thickest
Tropopause
the top surface of the troposphere
Stratosphere thickness
40 km thick, going up to 50 km from the surface fo the earth.
Stratosphere temperature _____ upward due to
increases due to absorption of solar UV by ozone
Stratopause
The upper boundary of the stratosphere
Mesosphere temperature
decreases upward as there is no ozone to absorb energy and particles are widely spaced
coldest point in the atmosphere
-100 degrees Celcius in mesosphere
Thermosphere temperature
High as it is directly exposed to sun, X-ray, and ultraviolet radiation absorption. However, the total heat content is low as the density is very low.
Ionosphere
The region where high-energy photons strip electrons from molecules, forming ionized gases forming the aurora borealis
Composition of modern atmosphere
nitrogen, oxygen, argon, and water vapour, and trace gases of CO2, O3, CH4 which are critical greenhouse gases
Aerosols in atmosphere
water droplets, ice particle, solid particles such as dust, salt, and carbon
The greenhouse effect steps:
- Solar radiation powers the climate system
- Some solar radiation is reflected by the Earth and the atmosphere and half is absorbed by the earth’s surface and warms it
- Infrared radiation is emitted from the earth’s surface
Different gases absorb different parts of the sun’s _____
energy spectrum
Absorbed energy is converted into ___ in the atmosphere
heats
Greenhouse gases
water, carbon dioxide, methane, N2O, and O3
Greenhouse gases ___ some of it’s long-wave radiation and ___ resulting in heating
absorb radiation and re-emit it
Earth emits most of it’s radiation in the:
15 micrometers band
why CO2 is a hazard
CO2 absorbs most of its energy at 15 micro-m band. As there is more CP2, oceans are evaporated and cause more water to be in the atmosphere resulting in more heat absorbed in the atmosphere.
Negative feedback of CO2
More evaporation of oceans forms more clouds. Clouds form more and in turn reflect more light making the earth cool.
