ATMO 1300-005 Class #4

Wednesday, 1/14/09 1

ATMO 1300-005 Class #4

Wednesday, January 14, 2009Chapter 1,2

Introduction, the energy cycle


Pressure in the different layers of the atmosphere

Layers of the atmosphere

• The Troposphere– Is the shallowest layer– Is the lowest layer– Has all the weather systems we call storms– Is shallowest (10 km or 6 miles) at the poles

in winter where the air column has lowest T – Is deepenst (16 km or 10 miles) in the tropics

where the air column has a highest T– Is usually a lapse layer—T decreases with ht


The Lapse Rate

• The lapse rate is the rate at which temperature decreases upward. The lapse rate is a positive number when the temperature decreases upward with increasing height (for example, 4°C/100 m). Temperature usually (but not always or everywhere) decreases with height in the troposphere.

• Sometimes the lapse rate is zero or <0.Wednesday, 1/14/09 4

Isothermal Layers

• When the lapse rate is zero, temperature is constant in a layer of the atmosphere. This is called an isothermal layer.

• At the top of the troposphere is an isothermal layer. This isothermal layer is called the tropopause. The decrease in temperature in the troposphere pauses, and the temperature is nearly constant before it changes upward.


Inversion Layers and the Stratosphere

• If the temperature increases upward with height, the layer is called an inversion layer, or simply and inversion.

• Inversions can occur in the troposphere, in particular places and at certain times, especially near the ground at night and in regions of high pressure over land.

• The stratosphere, which lies above the tropopause, is a deep inversion layer.


The upper atmosphere

• Temperature increases upward in the stratosphere because ozone absorbs energy from the sun.

• Above the layer with ozone is another isothermal layer, the stratopause.

• Above the stratopause is another lapse layer, the mesosphere. Above the mesosphere is another isothermal layer, the mesopause.


The top of the atmosphere and outer space

• The atmosphere does not have a well-defined top. It just gets thinner and thinner.

• Above the mesopause there are few molecules, atoms, and subatomic particles in the atmosphere. But these few particles are very energetic and move very fast.

• The temperature increases upward in the thermosphere, another inversion layer.


Surface Weather Maps

• Are coded to hold a lot of weather information

• Contain observations and analyses of observations

• Contain four different types of fronts• Use ºF only at the surface• Show pressure, winds, temperature,

precipitation, visibility, cloudiness, humidityWednesday, 1/14/09 9

Weather Map Codes


A simplified weather map


Chapter 2: The energy cycle

• Starts with the sun, which radiates mainly short waves on account of its extremely high temperature

• Continues with the propagation at the speed of light through space of energy in those waves

• Continues at the top of the atmosphere where several different things happen to the short-wave radiation


Yellow shows shortwave radiation in the energy budget


Rules of Radiation

• All objects emit radiation.• Objects at higher temperatures emit much

more radiation than objects at lower T.• Objects at higher T emit most of their

energy at shorter, more energetic wavelengths than objects at lower T.

• Radiation is absorbed, reflected, and transmitted. All three occur in Fig. 2.19.


Waves and wavelengths


Shortwave and longwave radiation


Earth and atmosphere emit longwave radiation


ATMO 1300-005 Class #4

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