Perhaps our sun has been discussed too much recently, so I promise this will be the last time for awhile, though mentioning it is necessary regarding future topics. I finish the introductory material with a brief discussion of major factors influencing observed weather characteristics, which includes affects of earth's orbit regarding solar energy collection, atmospheric composition, atmospheric layers, and basic global atmospheric and ocean circulations.

Earth's Orbit and Solar Energy Collection

Atmospheric Composition

Among very significant properties of the 2 primary gases are their chemical stability (they don't react with most natural substances - nitrogen much more so than oxygen, which does react well with some) and their thermal inactivity. Perhaps a good 'catch phrase' for them would be 'nonreactive and thermally inactive'. Physical objects such as plants, ground, and metals are very thermally active. Air is a poor medium for absorbing and emitting far infrared (terrestrial) radiation. Thus, air can remain rather mild during a 15-hour night, after frost quickly forms on surfaces. Air is nearly transparent to visible, near infrared, and very near ultraviolet radiation also. Water vapor is a variable component, and people often speak of air as consisting of dry air (less variable standard components) and water vapor. Many of less abundant constituents significantly affect Earth's energy exchange, and perhaps weather, more subtly. Ozone amount is variable, but less than hydrogen. You are probably aware of the greenhouse affect and its possible consequences regarding climate.

Atmospheric Layers

Atmospheric soundings reveal vertical regions with specific temperature characteristics :

Hydrostatic balance (which I plan discussion of later) requires that air density remain constant or decrease vertically. This does not imply warmest air aloft though, because vertically decreasing pressure allows densest surface air when a relatively small vertical temperature decrease is present. A quasi-limit for such is the dry adiabatic lapse rate, about 9.8 °C/km, more than which would violate hydrostatic balance.

Because of air's thermal inactivity, solar heating most efficiently occurs near ground, air mainly heated via conduction and then rising in convection currents. Thus, a positive temperature lapse rate (vertical decrease) is typical, especially during daytime. Such occurs in the lowest portion of our atmosphere, the troposphere, and would likely continue to outer space if not for thermal activity of atmospheric gases at greater altitudes. One of such gases is ozone (O₃), concentrated at 12-40 km altitudes. It very effectively absorbs high energy ultraviolet radiation, causing heating. Thus, temperature begins increasing vertically, becoming maximum near the top of the ozone region. Because such a temperature inversion greatly restricts vertical air motions, this layer is called the stratosphere (stratification sphere), and most weather is confined to the layer below called the troposphere (turning sphere). The hypothetical point where those layers meet is called the tropopause. As you may imagine, such is highest at equatorial regions where great convective vertical mixing occurs.

Above the ozone layer, temperature begins vertically decreasing in a region known as the mesosphere (middle sphere), the hypothetical point between it and the stratosphere called the stratopause. Noctilucent clouds sometimes occur in this region near arctic regions near Summer Solstice, sustained solar heating perhaps contributing to convection there, depositing trace amounts of water vapor. At altitudes about 80 km and above, atmospheric gases including diatomic nitrogen and oxygen absorb very energetic ultraviolet, X-ray, and gamma-ray solar energy, causing heating. Similar with the stratosphere, temperature vertically increases, but much more so, often becoming 600 °K or more during active solar periods. This layer called the thermosphere (thermal sphere) contains ionized atoms and aurorae previously mentioned. As you may guess, the mesopause is where the mesosphere and thermosphere meet. Above the thermosphere and (of course) thermopause is the exosphere (exit sphere) - a region at several hundred km altitude where earth's gravity no longer retains high energy absorbing atoms, which escape to outer space. This is the hypothetical top of the atmosphere, near the upper boundary I previously mentioned.

Text and embedded image are copyright of Joseph Bartlo, though may be used with proper crediting.