The Earth’s Atmosphere and Temperature 1&2

Chapter 4

The Earth’s Atmosphere

Breaking Down The Atmosphere

  • There are lots of different ways to break down or classify the atmosphere
  • Let’s start with the gaseous composition

Gaseous Composition

  • Break down by permanent gas content

























Break down by variable gas content





Water Vapor


0 to 4


Carbon Dioxide








Nitrous Oxide











.01 – .15





  • Note Ozone ppm is higher in the stratosphere (5-12 ppm)

Greenhouse Gases

  • The most abundant greenhouse gas is water vapor at 4% or less
  • It is considered a greenhouse gas because it traps heat
  • Consider what happens to temp when it is cloudy
  • Other greenhouse gases are Carbon Dioxide, Methane, Nitrous Oxide, and Chlorofluorocarbons

Vertical Structure by Temp.

  • The atmosphere reflects 55% of the sun’s energy, so only about 45% gets to earth
  • So one way to break down the atmosphere is by temperature
  • There are 5 layers:
  • Troposphere
  • Stratosphere
  • Mesosphere
  • Thermosphere
  • Exosphere
  • The half-way point of the atmosphere is at 18,000 feet or 3.5 miles


  • Starts at the surface and goes up to an average of 7 miles high (36,000 feet)
  • 20,000 ft at the poles to 65,000 at the equator
  • It is higher in the summer than winter
  • Lapse rate is 2 C/1000 or 3.5 f/1000


  • Boundary layer between troposphere and stratosphere
  • Signaled by  an abrupt change in the temp lapse rate
  • Isothermal air temp remains constant -57º C
  • This creates an inversion which keeps most wx below
  • The jet stream exists in occasional breaks in the tropopause.


  • Starts at about 39,000 ft
  • Temp doesn’t change much creating an inversion
  • This inversion keeps the Troposphere’s upward currents down
  • High amounts of ozone absorb the sun’s ultraviolet radiation and gives off heat
  • At 66,000 temps starts to rise because of the ozone absorbing energy


  • This is the boundary layer between the Stratosphere and the Mesosphere
  • It exists at about 164,000 ft


  • This one gets colder the further out
  • It exists at about 280,000 ft (31 to 53 miles high)
  • 99% of the atmosphere exists below this layer
  • There is little ozone up here therefore temps decrease with an increase in altitude.
  • Lowest average temp found at about 53 miles at -90º C or -130º F


  • This one gets warmer with an increase in altitude.
  • 53 to 310 miles
  • Radiation excites the oxygen molecule causing a temp increase.


  • 310 miles and further
  • Consists of atoms and molecules in loose orbit sometimes shooting off into space.

Atmosphere based on Gas

  • Homosphere
  • composition is fairly uniform
  • surface to 53 miles
  • Heterosphere
  • 53 miles and up
  • heavy atoms and molecules settle

Other Regions

  • Ionosphere
  • not really a layer
  • electrified region of the atmosphere
  • 37 miles is roughly the bottom
  • 180 miles is the greatest concentration
  • caused by the sun ionizing the atmosphere

Other Regions

  • Magnetosphere
  • Solar wind pushes it into the atmosphere
  • Increasing ionization making radio communication difficult

Aurora Borealis

  • 124 to 600 miles out
  • Atomic oxygen = green & red
  • Atomic nitrogen = red & violet

The Standard Atmosphere

  • Table 1-2 in the book

Chapter 5
Heat and Temperature


  • Temperature is the degree of hotness or coldness of a body or environment.
  • Measurement of the energy of the molecules (movement)
  • The faster the average speed of the molecular movement, the higher the temperature.
  • However, when might it be a 1000ºC and yet be very cold at the same time?

1000 Degrees and Freezing to Death

  • In order for our skin to detect a change in temp we must experience an extremely high number of molecules colliding into it.
  • At high altitudes, such as those in the Thermosphere, the temperature may be very “hot” (exceeding 1000ºC), but there aren’t enough molecules to warm the skin through conduction.
  • Molecules move an average of 1km before bumping into each other in the Thermosphere

Temp vs Heat

  • Heat is the total amount of kinetic energy of the atoms and molecules composing a substance
  • Since it is energy it can do work
  • Heat is measured using a calorimeter
  • Heat is measured in Joules
  • Temperature is the average kinetic energy
  • Temperature is measured with a thermometer
  • Temperature is measured in degrees
  • Heat flows from hot to cold

Temperature Scales

  • (Fº -32) then multiply by 5/9 =˚C
  • 5/9 is .55555556
  • (Cº * 9/5) then add 32 = Fº
  • 9/5 is 1.8

Heat Transfer Mechanisms

  • Radiation – Transfer of energy directly to the molecule from an outside source such as the sun.
  • Conduction – When one molecule bumps into another giving it some energy
  • Convection – Transfer of heat by mass movement of a fluid, like air currents or water currents (a thermal is a good example)

Specific heat

  • The measure of heat energy required to raise a substance to a new temperature
  • Different substances will warm at different rates when exposed to the same amount of heat energy
  • A substance with a low specific heat number warms more than one with a high number
  • Notice that water is going to change temp the slowest

Primary Cause of all Wx

  • Insolation is when the suns rays warm the earth
  • Different surfaces radiate and receive at different rates
  • Terrestrial radiation is when the earth radiates the energy back into the atmosphere
  • This is referred to as longwave radiation
  • The sun’s energy is referred to as shortwave radiation
  • Diurnal Variation is difference between day and night (coldest temp just after sunrise)

Controls of Temperature

  • Latitude
  • Land and water distribution
  • Ocean currents
  • Elevation

Daily Range of Temp

  • The daily range of temp is experienced closest to the ground.
  • The higher we go in altitude the less the change in temp
  • This takes place because the effects of terrestrial radiation are lessened
  • Likewise, areas close to large bodies of water experience less daily temp change

Ocean Currents

The largest daily temp range:

  • Browning Montana, January 23, 1916
  • Temp went from 44˚F to -56˚F in a 24 hour period
  • That is a temp change of 100˚F

Temperature and altitude

  • The lapse rate is a measure of the rate of change in temperature with an increase in altitude
  • Standard average lapse rate is 2°/1000
  • Dry adiabatic lapse rate is about 3°/1000
  • The only way to be sure is to take an atmospheric sounding
  • Gotten usually by using a radiosonde
  • Isothermal layer is a layer where the temperature remains constant with an increase in altitude
  • If the temperature increases with altitude it’s an inversion


  • Increase in temp with an increase in altitude
  • Can occur at any altitude in troposphere
  • Most common occurrence is on calm clear cool night in which the ground cools air close to it.
  • This is caused by terrestrial radiation and is referred to as a Radiation Inversion


  • This time of year the basin gets one
  • Cold stable air near the surface
  • Warm overriding air above
  • Smooth air
  • Poor visibility under the inversion
  • The most common inversion occurs near the ground on calm, clear, cool nights

Primary Cause of all Wx

  • Seasonal variation – summer to winter
  • Length of days and nights
  • Latitude variation – angle which the suns rays strike the earth
  • Topography variation – arid land Vs vegetation (wet / dry)
  • Ocean currents – The Gulf Stream

What causes a L or H pressure? 1

  • Temperature
  • In a closed container more temp = more pressure
  • You might think that the higher the temp the higher the pressure
  • But No!

What causes a L or H pressure? 1

  • Usually the highest pressures are found in cold regions
  • Why?
  • Because of Density
  • Usually the higher density offsets the lack of movement of the molecules

Density vs Pressure

  • Density = mass/volume
  • That is, the number of molecules in a given volume
  • Pressure = force/area
  • 14.7psi at sea level
  • That is the tiny push (force) the molecules makes when it bounces off something
  • More to come on this topic later

Pressure vs Density

  • As you can see most of the pressure and density is close to the surface
  • As we go higher the rate of decrease is less severe

What causes a L or H pressure? 2

  • Convergence
  • movement of air aloft is not always at the same speed
  • where it slows down it piles up into a H pressure
  • the piling up of air is called convergence

What causes a L or H pressure? 3

  • Divergence
  • opposite of convergence
  • the upper level wind speeds up and stretches the air out creating a L pressure
  • usually good wx under an upper level divergence

What causes a L or H pressure? 4

  • Thermal tides
  • At an average altitude of 60 mi (thermosphere) changes of over 500ºC
  • the rapid warming and cooling of upper air causes great density oscillations
  • shows up as small pressure changes at the surface because of the high altitude


  • Quiz on chapter 1 and 2
  • Quiz on the 50 states
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