GEOG 1114 Chapter 1
sulfur dioxide (SO2)
A colorless gas detected by its pungent odor; produced by the combustion of fossil fuels, especially coal, that contain sulfur as an impurity; can react in the atmosphere to form sulfuric acid, a component of acid deposition.
nitrogen dioxide (NO2)
A noxious (harmful) reddish-brown gas produced in combustion engines; can be damaging to human respiratory tracts and to plants; participates in photochemical reactions and acid deposition.
thermosphere
A region of the heterosphere extending from 80 to 480 km (50 to 300 mi) in altitude; contains the functional ionosphere layer.
temperature inverstion
A reversal of the normal decrease of temperature with increasing altitude; can occur anywhere from ground level up to several thousand meters; functions to block atmospheric convection and thereby trap pollutants.
homosphere
A zone of the atmosphere from Earth's surface up to 80 km (50 mi), composed of an even mixture of gases, including nitrogen, oxygen, argon, carbon dioxide, and trace gases.
industrial smog
Air pollution associated with coal-burning industries; it may contain sulfur oxides, particulates, carbon dioxide, and exotics.
photochemical smog
Air pollution produced by the interaction of ultraviolet light, nitrogen dioxide, and hydrocarbons; produces ozone and PAN through a series of complex photochemical reactions. Automobiles are the major source of the contributive gases.
electromagnetic spectrum
All the radiant energy produced by the Sun placed in an ordered range, divided according to wavelengths.
magnetosphere
Earth's magnetic force field, which is generated by dynamo-like motions within the planet's outer core; deflects the solar wind flow toward the upper atmosphere above each pole.
speed of light
Specifically, 299,792 km (186,282 mi) per second, or more than 9.4 trillion km (5.9 trillion mi) per year—a distance known as a light-year; at light speed, Earth is 8 minutes and 20 seconds from the Sun.
stratosphere
That portion of the homosphere that ranges from 20 to 50 km (12.5 to 30 mi) above Earth's surface, with temperatures ranging from -57°C (-70°F) at the tropopause to 0°C (32°F) at the stratopause. The functional ozonosphere is within the stratosphere.
normal lapse rate
The average rate of temperature decrease with increasing altitude in the lower atmosphere; an average value of 6.4 C° per km, or 1000 m (3.5 F° per 1000 ft). (Compare Environmental lapse rate.)
kinetic energy
The energy of motion in a body; derived from the vibration of the body's own movement and stated as temperature.
autumnal equinox
The fall or September equinox in the northern hemisphere, and the March equinox in the southern hemisphere. See March equinox and September equinox.
troposphere
The home of the biosphere; the lowest layer of the homosphere, containing approximately 90% of the total mass of the atmosphere; extends up to the tropopause; occurring at an altitude of 18 km (11 mi) at the equator, at 13 km (8 mi) in the middle latitudes, and at lower altitudes near the poles.
declination
The latitude that receives direct overhead (perpendicular) insolation on a particular day; the subsolar point migrates annually through 47° of latitude between the Tropics of Cancer (23.5° N) and Capricorn (23.5° S).
subsolar point
The only point receiving perpendicular insolation at a given moment—that is, the Sun is directly overhead. (See Declination.)
Tropic of Cancer
The parallel that marks the farthest north the subsolar point migrates during the year; 23.5° N latitude
Tropic of Capricorn
The parallel that marks the farthest south the subsolar point migrates during the year; 23.5° S latitude
oxygen
The second most common gas in the atmosphere, critical for most forms of life on Earth.
March equinox
The time around March 20-21 when the Sun's declination crosses the equatorial parallel (0° latitude) and all places on Earth experience days and nights of equal length (also known as vernal equinox). The Sun rises at the North Pole and sets at the South Pole. (Compare September equinox.)
vernal equinox
The time around March 20-21 when the Sun's declination crosses the equatorial parallel (0° latitude) and all places on Earth experience days and nights of equal length (also known as vernal equinox). The Sun rises at the North Pole and sets at the South Pole. (Compare September equinox.)
September equinox
The time around September 22-23 when the Sun's declination crosses the equatorial parallel (0° latitude) and all places on Earth experience days and nights of equal length (also known as autumnal equinox). The Sun rises at the South Pole and sets at the North Pole. (Compare March equinox.).
June solstice
The time when the Sun's declination is at the Tropic of Cancer, at 23.5 N latitude, on June 20-21 each year (also known as summer solstice). The day is 24 hours long north of the Arctic Circle. The night is 24 hours long south of the Antarctic Circle. (Compare December solstice.).
December solstice
The time when the Sun's declination is at the Tropic of Capricorn, at 23.5 S latitude, on December 21-22 each year (also known as winter solstice). The day is 24 hours long south of the Antarctic Circle. The night is 24 hours long north of the Arctic Circle. (Compare June solstice.)
rotation
The turning of Earth on its axis, averaging about 24 hours in duration; determines day-night relation; counterclockwise when viewed from above the North Pole and from west to east, or eastward, when viewed from above the equator.
mesosphere
The upper region of the homosphere from 50 to 80 km (30 to 50 mi) above the ground; designated by temperature criteria; atmosphere extremely rarified.
altitude
the angular distance between the horizon and the Sun
Milky Way Galaxy
A flattened, disk-shaped mass in space estimated to contain up to 400 billion stars; a barred-spiral galaxy; includes our Solar System.
ionosphere
A layer in the atmosphere above 80 km (50 mi) where gamma rays, X-rays, and some ultraviolet radiation are absorbed and converted into longer wavelengths and where the solar wind stimulates the auroras.
wavelength
A measurement of a wave; the distance between the crests of successive waves. The number of waves passing a fixed point in 1 second is called the frequency of the wavelength.
plane of the ecliptic
A plane (flat surface) intersecting all the points of Earth's orbit.
auroras
A spectacular glowing light display in the ionosphere, stimulated by the interaction of the solar wind with principally oxygen and nitrogen gases at high latitudes; called aurora borealis in the Northern Hemisphere and aurora australis in the Southern Hemisphere.
heterosphere
A zone of the atmosphere above the mesopause, from 80 km (50 mi) to 480 km (300 mi) in altitude; composed of rarefied layers of oxygen atoms and nitrogen molecules; includes the ionosphere.
tropopause
An average temperature of -57C defines the tropopause, it's upper limit, but its exact altitude varies with the season, latitude, and surface temperatures and pressures
exosphere
An extremely rarefied outer atmospheric halo beyond the thermopause at an altitude of 480 km (300 mi); probably composed of hydrogen and helium atoms, with some oxygen atoms and nitrogen molecules present near the thermopause.
solar wind
Clouds of ionized (charged) gases emitted by the Sun and traveling in all directions from the Sun's surface. Effects on Earth include auroras, disturbance of radio signals, and possible influences on weather.
day length
Duration of exposure to insolation, varying during the year depending on latitude; an important aspect of seasonality.
particulate matter (PM)
Dust, dirt, soot, salt, sulfate aerosols, fugitive natural particles, or other material particles suspended in air.
axial parallelism
Earth's axis remains aligned the same throughout the year (it "remains parallel to itself"); thus, the axis extended from the North Pole points into space always near Polaris, the North Star.
axial tilt
Earth's axis tilts 23.5° from a perpendicular to the plane of the ecliptic (plane of Earth's orbit around the Sun).
sensible heat
Heat that can be measured with a thermometer; a measure of the concentration of kinetic energy from molecular motion.
sunspots
Magnetic disturbances on the surface of the Sun, occurring in an average 11-year cycle; related flares, prominences, and outbreaks produce surges in solar wind.
pollutants
Natural or human-caused gases, particles, and other substances in the troposphere that accumulate in amounts harmful to humans or to the environment.
insolation
Solar radiation that is incoming to Earth systems.
winter solstice
The December solstice in the northern hemisphere, and the June solstice in the southern hemisphere. See June solstice and December solstice.
summer solstice
The June solstice in the northern hemisphere, and the December solstice in the southern hemisphere. See June solstice and December solstice.
environmental lapse rate
The actual rate of temperature decrease with increasing altitude in the lower atmosphere at any particular time under local weather conditions; may deviate above or below the normal lapse rate of 6.4 C° per km, or 1000 m (3.5 F° per 1000 ft). (Compare Normal lapse rate.)
solar constant
The amount of insolation intercepted by Earth on a surface perpendicular to the Sun's rays when Earth is at its average distance from the Sun; a value of 1372 W/m2 (1.968 calories/cm2) per minute; averaged over the entire globe at the thermopause.
revolution
The annual orbital movement of Earth about the Sun; determines the length of the year and the seasons.
axis
The imaginary line from the North Pole to the South Pole around which Earth rotates daily.
gravity
The mutual force exerted by the masses of objects that are attracted one to another and produced in an amount proportional to each object's mass.
fusion
The process of forcibly joining positively charged hydrogen and helium nuclei under extreme temperature and pressure; occurs naturally in thermonuclear reactions within stars, such as our Sun.
ozone layer
The region of the stratosphere that has higher levels of ozone (o3) that absorbs most of the Sun's ultraviolet radiation.
air
mixture of gases that is odorless, colorless, tasteless, and blended so thoroughly that it behaves as if it were a single gas
air pressure
pressure produced by the motion, size, and number of gas molecules in the air and exerted on surfaces in contact with the air; an average force at sea level of 1 kg/cm3
Antarctic Circle
the latitude denote the northernmost parallel (in the Southern Hemisphere) that experiences a 24-hour period of darkness in winder or daylight in summer
Arctic Circle
this latitude (66.5N) denotes the southernmost parallel (in the Northern Hemisphere) that experiences a 24-hour period of darkness in winter or daylight in summer
circle of illumination
The division between light and dark on Earth; a day-night great circle.
