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 Climate Change · Part One
 Climate Change · Part Two
 Introduction to Astronomy
 Life in the Universe

 Glossary: Climate Change
 Glossary: Astronomy
 Glossary: Life in Universe

    Glossary of Terms - S to Z
    Index: A to F | G to L | M to R | S to Z

    Saltzman, Barry -

    American climatologist currently at Yale University and a pioneer of modeling climate change. He has helped to develop a quantitative theory of large-scale climatic patterns and their evolution, based on the known laws of hydrodynamics and thermodynamics, taking into account the migratory high and low pressure systems of middle and high latititudes.

    Sarnthein, Michael -

    German paleoceanographer. He works on reconstruction of ice age climate from ocean sediments.

    Schneider, Stephen H. -

    American climatologist and a pioneer of three-dimensional climate modeling. He has written several popular books on climate change, including Laboratory Earth: The Planetary Gamble We Can't Afford to Lose. He was one of the scientists to speak out early on the risks associated with global warming.

    Scientific Notation - (n.)

    Sea breeze - (n.)

    The sea breeze is the familiar gentle wind from the sea that one experiences on a warm summer day. During hot summer days, it brings relief to coastal dwellers by blowing marine air inland. In the later afternoon, the sea breeze dies, and sometime at night the wind reverses, producing a land breeze. Sea and land breezes are caused by the difference in heat capacity of sea and land surface. During the day, when the sun shines both on the ocean and on the land surfaces, the land heats up much faster than the sea. The air above the land is heated from below and expands. As it expands, it becomes lighter than the surrounding air masses, and it rises. This same principle moves air up the smoke stacks and lifts hot-air balloons. The light rising air exerts less pressure on the land surface than did the air at equilibrium. Consequently, a low pressure center develops on the land surface. Air moves in from the periphery, along the pressure-gradient, from sea to land and the sea breeze is created. The rising air over the land, incidentally, keeps expanding and cools as it moves to ever-higher altitudes, until it begins to lose water, eventually forming clouds. On satellite photos,like the one below, the rising air is commonly clearly marked by puffy clouds over the coastal region, with a perfectly clear sky over the land.

    One reason for the unequal heating of land and sea is obvious: the great heat capacity of water. It takes 1000 calories to raise the temperature of one kilogram of water by 1°C, but only 200 calories to do the same for one kilogram of rock. Thus, given a certain influx of heat from the sun's radiation, a rock will warm up about 5 times faster than water. Conversely, rock will also cool faster at night compared with water. Consequently, the pressure gradient in the air reverses at night. Another reason for the unequal heating is both more subtle and more important than specific heat: the surface of the ocean, as far as diurnal heating is concerned, is much thicker than that of the land. The sunlight readily penetrates the ocean surface, and light is absorbed within a layer more than 10 meters thick. The thickness of the soil layer which is warmed by the sun (by downward conduction of surface heat) is more like 10 centimeters. The land surface is effectively more than 100 times thinner than the sea surface. Depending on the wetness of the soil, it is between 100 and 500 times less resistant to temperature change than the sea surface, given a certain solar radiation input. This makes it clear why diurnal temperature ranges in the deserts of California can readily go over 30°C, while those of the nearby ocean will rarely exceed a fraction of one degree.

    Seasons - (n.)

    The seasons in the middle and high latitudes depend on the variation in sunlight received throughout the year, as a result of the inclination of Earth's axis relative to the orbital plane. At northern summer solstice, the north pole of the Earth’s axis points toward the Sun, so that the Sun reaches its highest noontime position in the northern sky, being directly overhead at 23.5°N, at the tropic of Cancer. The day of northern summer solstice has the longest daylight in the year in the northern hemisphere, with the shortest night. At winter solstice, the north pole of the axis points away from the Sun, and the Sun reaches its lowest noontime position in the northern sky, being directly overhead at 23.5°S, at the tropic of Capricorn. The day of northern winter solstice has the shortest daylight on the northern hemisphere, and the longest night in the year. At equinox, the Sun is directly overhead at noontime on the Equator. The equinox following winter is called spring equinox, the one following summer is the fall equinox. During equinox, day and night are exactly of equal length everywhere on Earth. The seasons on northern and southern hemispheres are exactly opposite. The tropic of Cancer and the tropic of Capricorn get their names from a time when summer and winter solstice were reckoned by following the path of the Sun through the constellations of the zodiac, in the sky, rather than by looking in a printed calendar, as we do now. Though no longer the case, at that time the Sun was in the constellations Cancer and Capricorn during northern summer and winter solstice, respectively. (Puzzle: When was that?) Questions to ask yourself: How high above the horizon is the Sun at noon in Boulder, Colorado, on the day of northern summer solstice (Hint: Boulder is at 40°N.)? What about Oslo, Norway? From where can the midnight sun be seen on that day? How high above the horizon is the Sun at noon, in Boulder, on the day of northern winter solstice? What about Oslo, Norway? From where can the midnight sun be seen on that day?

    Sellers, W.D. -

    American climatologist. He was one of the first to apply mathematical climate models based on radiation balance.

    Sensible heat - (n.)

    The energy contained in a warm body, relative to a cold body of the same material and mass. Warm water that is heated in the tropics and cooled in high latitudes brings sensible heat toward the pole. Warm winds carry sensible heat from one place to another.

    Shackleton, Ernest -

    (1874-1922): Explorer famous for the failed Endurance expedition, which set out to the Weddell Sea in 1914 to land on its southern shore in an attempt to cross the Antarctic by sled. His ship was crushed in the pack ice, and the expedition members consisting of Shackleton and a crew of 27 men spent the winter on ice floes until they reached Elephant Island off the end of Palmer Peninsula. From there Shackleton set off with five selected men to cross the Drake Passage in a 22-foot boat, to reach the South Georgia Islands and find help for a rescue operation. Against all odds, all men were rescued and reached England safely. (For more information see the book, Endurance, by A. Lansing, Carroll and Graf, New York, 1959.)

    Shackleton, Nicklas J. -

    English paleoceanographer. Working with scientists from Lamont-Doherty Earth Observatory, he has applied Milankovitch theory to the reconstruction of ice age cycles from deep-sea sediments with emphasis on chronology. He has also contributed to our understanding of the marine carbon cycle by applying the carbon isotope record and extended high-resolution climate stratigraphy into pre-Quaternary time by applying Ocean Drilling Program materials.

    Scripps Institution of Oceanography (SIO) - (n.)

    The largest and oldest of the oceanographic institutes in the United States, SIO is engaged in a wide variety of studies concerning the solid Earth, the ocean and the atmosphere. Its prominent research includes the circulation of the ocean, waves and tides, earthquakes, carbon cycle chemistry, atmosphere and climate, ocean productivity, marine bacteria, and ocean sediments. Founded in 1903, its most renowned directors were the Norwegian oceanographer Harald U. Sverdrup (1888-1957) and the American geologist and geophysicist Roger R. Revelle (1909-1991).

    Smagorinski, J. -

    American climatologist who helped pioneer climate physics and modeling in the 1960’s.

    Solar constant - (n.)

    The amount of energy received from the Sun at the top of the atmosphere, per time unit and per unit area. The value of the constant is near 2 cal/cm2 per second, which corresponds to about 1350 watts per square meter. The solar "constant" is actually thought to vary by at least 0.1 percent on time scales of decades and perhaps by as much as 0.5 percent on time scales of centuries.

    Solomon, Susan -

    American atmospheric chemist. She is a leader in research on the ozone hole in the Antarctic. She led the team of scientists that measured chlorine dioxide, which was among the first chemical observations showing that chlorine from chlorofluorocarbons was the cause of the ozone hole.

    Some Chemical Symbols - (n.)

    O2: molecular oxygen

    O3: ozone

    N2: molecular nitrogen

    N2O: nitrous oxide

    NO: nitric oxide

    NO3: nitrate radical

    NOx: Sum of NO and NO2

    NO3- : nitrate ion

    HNO3: nitric acid

    NH3: ammonia

    NH4+ : ammonium ion

    H2: molecular hydrogen

    H2O: water

    OH: hydroxyl

    HO2: hydroperoxyl

    HOx: the sum OH and HO2

    C: carbon; there are 3 isotopes: 12C, 13C, 14C

    CO: carbon monoxide

    CO2: carbon dioxide

    F2: molecular fluorine

    Cl2: molecular chlorine

    Br2: molecular bromine

    CFC: chlorofluorocarbon

    CFC-11: CFCl3 or trichlorofluoromethane

    CFC-12: CF2Cl2 or dichlorodifluoromethane

    CFC-113: C2F3Cl2 or trichlorotrifluoroethane

    CFC-114: C2F4Cl2 or dichlorotetrafluoroethane

    CFC-115: C2F5Cl or chloropentafluoroethane

    Index: A to F | G to L | M to R | S to Z

    Spectrum - (n.)

    A plot of wavelengths (or equivalent measures of cyclicity) against amplitude (or other measures of energy content). For visible light, the spectrum includes all colors between violet and dark red. For electromagnetic radiation, the spectrum includes everything from gamma radiation and x-rays to radio waves, with visible light in between. For water waves, the spectrum includes everything between wind ripples to tides. For seismic waves, the spectrum ranges from barely noticeable vibrations to the great long-wave oscillations that are so dangerous to buildings. For climate fluctuations, the spectrum spans the gamut from daily temperature fluctuations to annual seasons to the great ice age cycles. Everything we know about distant stars and galaxies comes from analyzing the spectrum of their electromagnetic radiation, and almost everything we know about the interior of the Earth comes from analyzing the spectrum of various types of seismic waves. The mathematics of spectral analysis are based on the work of the great French physicist and mathematician J.B. Fourier (1768-1830).

    Starr, V.P. -

    American climatologist who completed classic studies on the physics of climate.

    Suess, Hans -

    (1909-1989): Austrian-American chemist. He determined the amount of radioactive carbon in the ocean to find out how fast carbon dioxide in the atmosphere exchanges with the ocean's reservoir. Suess also worked on the radiocarbon content in tree-rings, finding a short-term variability (called "Suess wiggles") which he explained as indicating that climate changes occur on a decadal scale.

    Sverdrup, Harald U. -

    (1888-1957): Norwegian oceanographer and Arctic explorer. A professor of geophysics at the University of Oslo and director of the Norsk Polarinstitutt and director of Scripps Institution of Oceanography from 1936-1948. Sverdrup made fundamental contributions to the understanding of the circulation of the ocean and was the lead author of the textbook that defined the modern field of oceanography (Sverdrup, H. U., M. Johnson, R. H. Fleming, The Oceans, their physics, chemistry, and general biology. Prentice-Hall, Englewood Cliffs, 1942.).

    Temperature Units - (n.)

    Degrees Celsius (°C): Introduced by a Swedish astronomer, Andres Celsius, 1°C is defined as 1/100 of the temperature difference between water freezing point and boiling point by a pressure of 1 atmosphere. The thermometer freezing point is 0° and the boiling point is 100°.

    Degrees Fahrenheit (°F): Named for the German-born scientist, Gabriel Daniel Fahrenheit, 1 °F is defined as 1/180 of the temperature difference between water freezing point and boiling point. The thermometer freezing point is 32° and the boiling point is 212°.

    Degrees Kelvin (°K): Invented by William Thomson, Lord Kelvin, a 19th Century British scientist, this scale is based upon the fact that the coldest it can get (theoretically) is -273.15 degrees Celsius. The value, -273.15 degrees Celsius, is called "absolute zero." At this temperature it is thought that molecular motion stops. Since it cannot get any colder than –273.15 °C, the Kelvin scale uses this number as zero. Its unit, the degree Kelvin, is equal to the degree Celsius.

    Conversion Equations:
    1. To convert Fahrenheit to Celsius use:
           Celsius = (Fahrenheit – 32) * 5/9

    2. To convert Celsius to Fahrenheit use:
           Fahrenheit = (Celsius * 9/5) +32

    3. To convert Celsius to Kelvin use:
           Kelvin = Celsius + 273

    Thermocline - (n.)

    A rapid change in the temperature of water from the ocean surface to the ocean floor.

    Thermokarst - (n.)

    a range of features formed in areas of low relief in the tundra when permafrost with excess ice thaws. Thermokarst terrain is made of irregular depressions and include features such as mud flows on sloping ground and other forms of thaw settlement that account for many of the engineering problems found in tundra landscapes. Global warming may result in irregular melting of the permafrost, resulting in an increase in this terrain. See also “permafrost.”

    Time Units - (n.)

    bp: (years) before present

    kbp: thousands of years before present

    mbp: millions of years before present

    Toon, Brian O. -

    American climatologist who modeled the climate that would result from a "nuclear winter."

    Trade winds - (n.)

    Air flow from east to west and toward the equator (or the Intertropical Convergence Zone) roughly in the zone between the tropics of Cancer and Capricorn, although it can blow somewhat beyond those latitudes in some places. The trades got their name from English sailors, for their steadiness (as in the phrase, "the wind blows trade," i.e. on track). See also “General Circulation of the Atmosphere.”

    Upwelling - (n.)

    Upwelling is a process whereby cold water from below the warm surface layer comes to the sunlit zone, where the cold nutrient-rich water causes much growth of microscopic plankton, which feeds zooplankton, which in turn feeds fish. Upwelling regions, therefore, are favorite fishing areas. Most of the upwelling in the ocean occurs in two settings: along the shores bathed by eastern boundary currents (the eastern portions of the great central gyres) and along the equator. Normally, the upwelling water derives from depths between 100 and 300 m, a factor that depends on the strength of the upwelling motion. Upwelling is driven by winds and both the coastal upwelling along the eastern boundary currents and equatorial upwelling rely on the trade winds. See also “Coastal Upwelling.”

    Ultraviolet light - (n.)

    Also known as UV light, this form of electromagnetic radiation is emitted by the Sun and is invisible to the naked eye. Lying in the electromagnetic spectrum between violet light and X-rays, UV light can be harmful to living organisms, most notably by damaging DNA. UV light comes in three main forms: UV-A, UV-B, and UV-C. UV-C is the shortest and most dangerous wavelength, but it is largely absorbed by the Earth's ozone layer. UV-A, a longer wavelength, usually induces skin tanning in humans, while UV-B, a shorter wavelength, causes sunburns and is most often associated with skin cancer in humans. While the Earth’s ozone layer absorbs about half of the UV-B radiation, UV-A radiation is not absorbed by our atmosphere.

    van Loon, Harry -

    (born 1925): Climatologist who has made contributions to the understanding of climate oscillations.

    Vernadsky, Vladimir -

    (1863-1945): Russian geochemist and mineralogists. He introduced the notion that life processes control the chemistry of the surface of the Earth and is regarded as the founder of the theory of the biosphere.

    Wallace, John M. -

    Climatologist at the University of Washington. His work has improved our understanding of global climate and its year-to-year and decade-to-decade variations, including ENSO and climate oscillations, by making use of observational data.

    Index: A to F | G to L | M to R | S to Z

    Warm pool - (n.)

    In the western equatorial Pacific, this is a region of warm surface waters with a temperature close to 29°C (85°F) and covers an area roughly the size of North America. Normally, the warm pool is fed by Pacific trade winds moving warm tropical surface waters to the west, piling it up in the region between Indonesia, the Philippines, and New Guinea. Warm water gives off heat and moisture to the atmosphere, so the western tropical region becomes a great center for convection and rainfall on the globe. Also, the heat from the warm pool feeds energy to tropical storms there. For reasons yet unknown, during certain years, the trade-winds weaken, and warm surface water is no longer carried westward. On the contrary, the piled-up warm-pool water starts moving east, taking the convection region with it. The surface waters in the eastern region become warm, and now suddenly the tropical storms occur in the region of Tahiti. The coral there suffer from being too warm, and shed their color-giving algal symbionts. In contrast, drought strikes in the western areas, which are no longer in the convection center (e.g. New Guinea and Indonesia). This change in condition produces the "El Niño" effect. See also “El Niño”

    Washington, W. M. -

    Climatologist at NCAR (National Center for Atmospheric Research) in Boulder, Colorado. He is a leading expert in three-dimensional modeling of climate change.

    Water and heat storage - (n.)

    How does water react to heating or cooling? How much energy can it store? It turns out that water is much more efficient in storing heat than any other common substance on Earth. To increase the temperature of fluid water by one degree Centigrade takes one calorie of heat energy for each gram of water. To do the same for a rock, for comparison, takes 0.2 calories per gram, and for petroleum requires 0.5 calories per gram. To change a gram of ice into water (without increasing the temperature) takes 80 calories. Conversely, when water freezes, it releases this amount of heat into the environment. To change a gram of water into vapor takes 580 calories. This means that evaporation is the best cooling mechanism around! Our body takes advantage of this fact when cooling itself by sweating: the evaporation of the sweat extracts heat from the surroundings, lowering the temperature of the skin. The heat expended in the phase change of water to vapor is not lost, but is contained in the vapor in a latent form. When the vapor condenses, the heat is freed for warming the surrounding air. This release of heat during condensation is the ultimate driving force for hurricanes.

    The phase changes of water combined with its unique heat-related properties are intimately involved in all aspects of climate and weather. Water transfers and stores heat on an immense scale, and thereby evens out the temperature differences between day and night, summer and winter, and tropics and polar areas. Consider the temperature differences between day and night: they are largest in the water-starved desert, whereas in areas where water is abundant evaporation during the day tends to lower the temperature, and condensation during the night (the familiar dew) tends to raise it. During the day, clouds protect the ground from the heat of the sun, and at night, from the black coldness of space. Seasonal differences are similarly tempered by the great heat reserves of water, hence the mildness of coastal climates. Likewise, geographic differences are moderated by the transfer of heat through water motion and water phase changes. Most of this transfer is by water vapor in the air. Warm winds blowing over warm ocean regions pick up the water, cooling the sea surface. In cold regions, the air becomes unable to hold the vapor. The vapor condenses and gives off its heat of evaporation. If it freezes to snow, it also gives off its heat of fusion, to the surrounding air. Thus, a blizzard brings warmth: a somewhat unexpected conclusion, perhaps, to those who have been surprised by a snowstorm during a hike in the mountains.

    Westerlies - (n.)

    Near-surface winds blowing from the west, toward the equatorial portion of the "polar front" regions, where cold air from high latitudes meets the warmer air from the temperate latitudes. Westerlies typically carry cyclonic disturbances eastward.

    Wyrtki, Klaus -

    Oceanographer at the Geophysical Institute in Hawaii. He has pioneered studies on the ENSO phenomenon in the central Pacific.

    Zooplankton - (n.)

    A large variety of non-photosynthesizing organisms comprise the zooplankton, creatures that drift with the currents at all depths in the ocean. Zooplankton is concentrated especially in surface waters, where they feeds on phytoplankton. The smallest zooplankton consists of unicellular organisms such as foraminifers and radiolarians. The most commonly caught zooplankton, using nets with a mesh of 0.5 mm, consists of various kinds of copepods and other small crustaceans, like Antarctic krill. The largest zooplankton are among the jellyfish, which reach a diameter of several feet, and trail tentacles tens of feet long to ensnare smaller zooplankton and small fish.

    Index: A to F | G to L | M to R | S to Z


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