Chapter 2 Physical Processes On Earth PDF

CHAPTER 2: PHYSICAL PROCESSES ON EARTH Introduction Solar energy - The atmosphere the layer of the Earth that serve as protecting envelope and hence its natural consistencies are to be maintained. Global warming -Imbalance in solar energy distribution as with the increase in greenhou...

CHAPTER 2: PHYSICAL PROCESSES ON EARTH Introduction Solar energy - The atmosphere the layer of the Earth that serve as protecting envelope and hence its natural consistencies are to be maintained. Global warming -Imbalance in solar energy distribution as with the increase in greenhouse gases maximizing the greenhouse effect. Hydrological cycle - is the process of moving and transforming water molecules from liquid to vapor and back to liquid again. Condensation above the earth’s surface produces clouds.  3. LEARNING OUTCOME At the end of Chapter 2, you are expected to be able to: a)identify different physical processes on Earth that affects climate and climate change. b)define the effects and impacts of solar energy, atmosphere, earth system, water cycle and cloud formation to the changing climate. c)analyze how these factors affects lives on earth and d) evaluate the impacts of human activities that affects these factors that continually changes the climate system of the Earth.  LEARNING CONTENT Nature of Solar Energy Solar zenithal angle: angle formed by the direction of the sun and the local vertical. Radiant energy: amount of energy that is transferred by radiation. It is expressed in J (Joule).  Extra-terrestrial radiation, irradiance Spectral distribution of the irradiance: or irradiation: The total radiation, The distribution of the irradiance as a irradiance and irradiation originating function of the wavelength. from the sun impinging on a Total irradiance, irradiation: The horizontal surface located at the top irradiance, irradiation, integrated over of the atmosphere. the whole spectrum.  SOLAR RADIATION AT THE TOP OF THE ATMOSPHERE Solar radiation- Other sources which are all negligible relative to solar radiation are: the geothermal heat flux generated by the earth interior natural terrestrial radioactivity, and cosmic radiation Solar radiation Økey factor controlling the climate of the earth. ØThere is a global radiative equilibrium between the earth and extra-terrestrial space. Øthe part of the incoming solar radiation that is absorbed by the earth and its atmosphere is equal to the outgoing longwave radiation from the earth and its atmosphere.  SOLAR RADIATION AT GROUND LEVEL As the solar radiation makes its way from the top of the atmosphere downwards the ground, it is depleted when passing through the atmosphere due to interactions with the constituents of the atmosphere. On average, less than half of extra-terrestrial radiation reaches ground level. The description and modelling of the optical processes affecting the solar radiation within the atmosphere is called radiative transfer Absorption is a process present in the atmosphere whereby the energy absorbed by a constituent at a given wavelength is converted into another form and is no longer present in the light. Absorption may occur at very specific wavelengths, called absorption lines or may occur over a wide continuum of wavelengths. Scattering is a physical process associated with light and its interaction with matter occurring at all wavelengths. Particles and molecules deflect the incident wave and re-radiate that energy in all directions, thus abstracting energy from the incident wave. The scattering pattern indicates the relative probability of a photon to be scattered in a given direction; it depends on the size of the particle or molecule, its shape and other properties, and on the incident wavelength.  THE ATMOSPHERE a delicate life-giving blanket of air that surrounds the fragile earth. it influences everything we see and hear—it is intimately connected to our lives. Living on the surface of the earth, we have adapted so completely to our environment of air that we sometimes forget how truly remarkable this substance is. Even though air is tasteless, odorless, and (most of the time) invisible, it protects us from the scorching rays of the sun and provides us with a mixture of gases that allows life to flourish. The earth’s atmosphere is a thin, gaseous envelope comprised mostly of nitrogen (N2) and oxygen (O2), with small amounts of other gases, such as water vapor (H2O) and carbon dioxide (CO2). Nested in the atmosphere are clouds of liquid water and ice crystals.  The thin blue area near the horizon below represents the most dense part of the atmosphere. Although our atmosphere extends upward for many hundreds of kilometers, almost 99 percent of the atmosphere lies within a mere 30 km (about 19 mi) of the earth’s surface. This thin blanket of air constantly shields the surface and its inhabitants from the sun’s dangerous ultraviolet radiant energy, as well as from the onslaught of material from interplanetary space. There is no definite upper limit to the atmosphere; rather, it becomes thinner and thinner, eventually merging with empty space, which surrounds all the planets.  COMPOSITION OF THE ATMOSPHERE The concentration of the invisible gas water vapor, however, varies greatly from place to place, and from time to time. Close to the surface in warm, steamy, tropical locations, water vapor may account for up to 4 percent of the atmospheric gases. The changing of water vapor into liquid water is called condensation, whereas the process of liquid water becoming water vapor is called evaporation. *Source: Essentials of Meteorology: An invitation to the Atmosphere, 2001  Water vapor - an extremely important gas in our atmosphere. Not only does it form into both liquid and solid cloud particles that grow in size and fall to earth as precipitation, but it also releases large amounts of heat— called latent heat—when it changes from vapor into liquid water or ice. Latent heat -an important source of atmospheric energy, especially for storms, such as thunderstorms and hurricanes. Moreover, w a t e r v a po r i s a po t e n t g r e e n h o u s e g a s because it strongly absorbs a portion of the earth’s outgoing radiant energy. Thus, water vapor plays a significant role in the earth’s heat energy balance. LAYERS OF THE ATMOSPHERE  LAYERS OF THE ATMOSPHERE Troposphere Ø region of the atmosphere from the surface up to about 11 km contains all of the weather we are familiar with on earth. Ø region is kept well stirred by rising and descending air currents. Ø common for air molecules to circulate through a depth of more than 10 km in just a few days. Ø region of circulating air extending upward from the earth’s surface to where the air stops becoming colder wit h h e i g h t i s c a l le d t h e troposphere— from the Greek tropein, meaning to turn, or to change. Ø region contains the air we breathe and is like the stage for meteorology and climate.  STRATOSPHERE region, where the air temperature remains constant with height, is referred to as an isothermal (equal temperature) zone. The bottom of this zone marks the top of the troposphere and the beginning of another layer, the stratosphere. The boundary separating the troposphere from the stratosphere is called the tropopause.  MESOSPHERE Above the stratosphere is the mesosphere (middle sphere). air here is extremely thin and the atmospheric pressure is quite low. Even though the percentage of nitrogen and oxygen in the mesosphere is about the same as it was at the earth’s surface, a breath of mesospheric air contains far fewer oxygen molecules than a breath of tropospheric air. At this level, without proper oxygen- breathing equipment, the brain would soon become oxygen-starve d— a c ondition known as hypoxia—and suffocation would result. With an average temperature of –90°C, the top of the mesosphere represents the coldest part of our atmosphere.  THERMOSPHERE “hot layer” above the mesosphere. Here, oxygen molecules (O2) absorb energetic solar rays, warming the air there are relatively few atoms and molecules. the absorption of a small amount of energetic solar energy can cause a large increase in air temperature that may exceed 500°C, or 900°F.  IONOSPHERE EXOSPHERE ü is not really a layer, but rather an electrified region within the upper atmosphere where fairly large concentrations of ions and free electrons exist. region where atoms and ü plays a major role in radio communications. molecules shoot off into space ü The lower part (called the D region) reflects is sometimes referred to as the standard AM radio waves back to earth, but at the exosphere, which represents same time it seriously weakens them through the upper limit of our absorption. atmosphere. ü At night, though, the D region gradually disappears and AM radio waves are able to  penetrate higher into the ionosphere (into the E and F regions), where the waves are reflected back to earth. Because there is, at night, little absorption of radio waves in the higher reaches of the ionosphere, such waves bounce repeatedly from the ionosphere to the earth’s surface and back to the ionosphere again. In this way, standard AM radio waves are able to travel for many hundreds of kilometers at night. *Image source: Essentials of Meteorology: An invitation to the Atmosphere, 2001  EARTH SYSTEM Earth - our home and habitat. The Earth is approximately 4.6 billion years old. Interdisciplinary study of the earth's naturally occurring phenomena, its processes and evolution. Earth Science by necessity involves the marriage of a number of specialty sciences.  SPECIALTY SCIENCES a. Astronomy- study of the origin, evolution and composition of the universe, solar system and planetary bodies. Cosmology: origin of the universe Astrogeology: comparison of extra-terrestrial planetary bodies with the earth Astrophysics: quantitative study of the physical nature of the universe B. GEOLOGY- STUDY OF THE EARTH, ITS COMPOSITION, ORIGIN, EVOLUTION AND PROCESSES. Mineralogy/Petrology: study of rocks and minerals. Geophysics: study of earth physics and processes. Volcanology: study of volcanoes. Seismology: study of earthquakes and seismic waves. Geomorphology: study of surface processes and landforms. Paleontology/Historical Geology: study of past life and historical evolution of the earth through time. Plate Tectonics TECTONIC PLATES MAP SHOWING THE RING OF FIRE c. Meteorology: Study of atmospheric phenomena Climatology: Study of geographic climate patterns: processes and causes § Future Climate Prediction § Paleoclimatology Weather studies and weather prediction Storm Prediction and Emergency Management Atmospheric Science: study of physics and chemistry of earth's atmosphere § Environmental/Air Pollution Control d. Oceanography: study of earth's ocean systems Earth's surface covered by 70% ocean water... hence the reference to the "Blue Planet". Study of ocean chemistry and circulation patterns Physical study of seafloor  ENVIRONMENTAL SPHERES OF THE EARTH The earth can be subdivided into spheres" of composition represented by the complex interface of four principal components of the environment: ØLithosphere ØAtmosphere ØHydrosphere ØBiosphere.  A. The Geosphere: comprised of the solid, inorganic portion of the earth's framework including elements to form atoms to form minerals to form rocks (1) Lithosphere and Interior of the Solid Earth - The earth is comprised of a series of compositionally distinct shells of rock. (a) inner core, a solid iron-rich zone with a radius of 1216 km (b) outer core, a molten metallic layer 2270 km thick (c) mantle, a solid rocky layer 2885 km thick  B. THE ATMOSPHERE: Øthe gaseous envelope of air that surrounds the earth (1) a thick envelope of air that surrounds the earth's surface. Provides the air we breathe, together coupled with the sun's energy, drives our climatic and weather systems. (2)Troposphere-Stratosphere-Mesosphere-Thermosphere  C. THE HYDROSPHERE Øthe waters of the earth including ground water (beneath the surface), surface water (rivers, streams, lakes, oceans), and water locked up as ice in the form of glaciers. (1) the water and liquid that is present on the earth's surface, in its atmosphere, and beneath its surface. (2) Oceans cover 71% of the earth's surface and contain 97% of the earth's water. (3) Water cycles from the oceans to the air via evaporation, moves to land, precipitates as rain/snow, partially infiltrates the earth's surface, and eventually flows back to oceans via rivers.  D. BIOSPHERE: Øall living matter and cellular tissue on the earth, in the form of plant and animal, both microscopic and macroscopic. (1) All life on the planet is contained within its uppermost layer of the earth, including its atmosphere. (2) the vast majority of all earthly life inhabits a zone less than 3 miles thick, and the total vertical extent of the life zone is less than 20 miles.  HYDROLOGICAL CYCLE AND CLOUDS Within the atmosphere, there is a continuous circulation of water. Here, the sun’s energy transforms enormous quantities of liquid water into water vapor in a process called evaporation. Winds then transport the moist air to other regions, where the water vapor changes back into liquid, forming clouds, in a process called condensation. Under certain conditions, the liquid (or solid) cloud particles may grow in size and fall to the surface as precipitation—rain, snow, or hail. If the precipitation falls into an ocean, the water is ready to begin its cycle again. If, on the other hand, the precipitation falls on a continent, a great deal of the water returns to the ocean in a complex journey. hydrologic (water) cycle- cycle of moving and transforming water molecules from liquid to vapor and back to liquid again. In the most simplistic form of this cycle, water molecules travel from ocean to atmosphere to land and then back to the ocean.  For example, before falling rain ever reaches the ground, a portion of it evaporates back into the air. Some of the precipitation may be intercepted by vegetation, where it evaporates or drips to the ground long after a storm has ended. Once on the surface, a portion of the water soaks into the ground by percolating downward through small openings in the soil and rock, forming groundwater that can be tapped by wells. What does not soak in collects in puddles of standing water or runs off into streams and rivers, which find their way back to the ocean  CLOUDS visible aggregate of tiny water droplets or ice crystals suspended in the air. Some are found only at high elevations, whereas others nearly touch the ground. Clouds can be thick or thin, big or little—they exist in a seemingly endless variety of forms. To impose order on this variety, we divide clouds into ten basic types.  CLASSIFICATION OF CLOUDS Lamarck (1744–1829)- first person to propose the first system of cloud classification is the French naturalist in 1802. However, his system did receive good acclaim to many. A year later, an English naturalist named Luke Howard, developed a cloud classification system that found general acceptance. Howard’s innovative system employed Latin words to describe clouds as they appear to a ground observer. He named a sheet-like cloud stratus (Latin for “layer”); a puffy cloud cumulus (“heap”); a wispy cloud cirrus (“curl of hair”); and a rain cloud nimbus (“violent rain”). In Howard’s system, these were the four basic cloud forms. Other clouds could be described by combining the basic types.  In 1887, Abercromby and Hildebrandsson expanded Howard’s original system and published a classification system that, with only slight modification, is still used today. Ten principal cloud forms are divided into four primary cloud groups. Each group is identified by the height of the cloud’s base above the surface: high clouds, middle clouds, and low clouds. The fourth group contains clouds showing more vertical than horizontal development. Within each group, cloud types are identified by their appearance.  FOUR MAJOR CLOUD GROUP AND 1.High clouds THEIR TYPES a.Cirrus (Ci) b.Cirrostratus (Cs) c.Cirrocumulus (Cc) 2.Middle clouds a.Altostratus (As) b.Altocumulus (Ac) 3.Low clouds a.Stratus (St) b.Stratocumulus (Sc) c.Nimbostratus (Ns) 4.Clouds with vertical development a.Cumulus (Cu) b.Cumulonimbus (Cb) APPROXIMATE HEIGHT OF CLOUD BASES ABOVE THE SURFACE OF VARIOUS LOCATIONS *Source: Essentials of Meteorology: An invitation to the Atmosphere, 2001  Large temperature changes cause most of this latitudinal variation. For example, high cirriform clouds are composed almost entirely of ice crystals. In subtropical regions, air temperatures low enough to freeze all liquid water usually occur only above about 20,000 feet. Clouds cannot be accurately identified strictly on the basis of elevation. Other visual clues are necessary. Some of these are explained in the following section.  CLOUD IDENTIFICATION High Clouds High clouds in middle and low Cirrus High clouds usually appear white, except near sunrise latitudes generally form above and sunset, when the unscattered (red, orange, and 20,000 ft (or 6000 m). Because the yellow) components of sunlight are reflected from the air at these elevations is quite underside of the clouds. cold and “dry,” high clouds are § most common high clouds are the cirrus, which are thin, composed almost exclusively of wispy clouds blown by high winds into long streamers ice crystals and are also rather called mares’ tails. thin. usually move across the sky from west to east, indicating the prevailing winds at their elevation. CIRROCUMULUS CLOUDS seen less frequently than cirrus, appear as small, rounded, white puffs that may occur individually, or in long rows. When in rows, the cirrocumulus cloud has a rippling appearance that distinguishes it from the silky look of the cirrus and the sheet-like cirrostratus. Cirrocumulus seldom cover more than a small portion of the sky. The dappled cloud elements that reflect the red or yellow light of a setting sun make this one of the most beautiful of all clouds. The small ripples in the cirrocumulus strongly resemble the scales of a fish; hence, the expression “mackerel sky” commonly describes a sky full of cirrocumulus clouds.  CIRROSTRATUS thin, sheetlike, high clouds that often cover the entire sky Ice crystals in these clouds bend the light passing through them and will often produce a halo. The veil of cirrostratus may be so thin that a halo is the only clue to its presence. Thick cirrostratus clouds give the sky a glary white appearance and frequently form ahead of an advancing storm *Image source: Essentials of Meteorology: An invitation to the Atmosphere, 2001  MIDDLE CLOUDS bases between about Altocumulus 6500 and 23,000 ft (2000 and 7000 m) in the middle latitudes. composed of water droplets and—when the temperature becomes low enough— some ice crystals. *Image source: Essentials of Meteorology: An invitation to the Atmosphere, 2001  ALTOSTRATUS a gray or blue-gray cloud that often covers the entire sky over an area that extends over many hundreds of square kilometers. In the thinner section of the cloud, the sun (or moon) may be dimly visible as a round disk, which is sometimes referred to as a “watery sun”.  The fact that halos only occur with cirriform clouds also helps one distinguish them. Another way to separate the two is to look at the ground for shadows. If there are none, it is a good bet that the cloud is altostratus because cirrostratus are usually transparent enough to produce them. Altostratus clouds often form ahead of storms having widespread and relatively continuous precipitation. If precipitation falls from an altostratus, its base usually lowers. If the precipitation reaches the ground, the cloud is then classified as nimbostratus. Low Clouds Low clouds, with their bases lying below 6500 ft (or 2000 m) are almost always composed of water droplets; However, in cold weather, they may contain ice particles and snow.  NIMBOSTRATUS a dark gray, “wet”-looking cloud layer associated with more or less continuously falling rain or snow. The intensity of this precipitation is usually light or moderate—it is never of the heavy, showery variety. The base of the nimbostratus cloud is normally impossible to identify clearly and is easily confused with the altostratus. Thin nimbostratus is usually darker gray than thick altostratus, and you cannot see the sun or moon through a layer of nimbostratus. *Image source: Essentials of Meteorology: An invitation to the Atmosphere, 2001 q Visibility below a nimbostratus cloud deck is usually quite poor because rain will evaporate and mix with the air in this region. q If this air becomes saturated, a lower layer of clouds or fog may form beneath the original cloud base. q Since these lower clouds drift rapidly with the wind, they form irregular shreds with a ragged appearance called stratus fractus, or scud.  STRATOCUMULUS A low, lumpy cloud layer It appears in rows, in patches, or as rounded masses with blue sky visible between the individual cloud elements. Often they appear near sunset as the spreading remains of a much larger cumulus cloud. The color of ranges from light to dark gray. It differs from altocumulus in that it has a lower base and larger individual cloud elements. To distinguish between the two, hold your hand at arm’s length and point toward the cloud. Altocumulus cloud elements will generally be about the size of your thumbnail; stratocumulus cloud elements will usually be about the size of your fist. Rain or snow rarely falls from stratocumulus.  uniform grayish cloud that often covers the entire sky. resembles a fog that does not reach the ground. STRATUS Actually, when a thick fog “lifts,” the resulting cloud is a deck of low stratus. Normally, no precipitation falls from the stratus, but sometimes it is accompanied by a light mist or drizzle. This cloud commonly occurs over Pacific and Atlantic coastal waters in summer. A thick layer of stratus might be confused with nimbostratus, but the distinction between them can be made by observing the base of the cloud. Often, stratus has a more uniform base than does nimbostratus. Also, a deck of stratus may be confused with a layer of altostratus. However, if you remember that stratus clouds are lower and darker gray, the distinction can be made.  CLOUDS WITH VERTICAL DEVELOPMENT Cumulus q puffy cumulus cloud takes on a variety of shapes, but most often it looks like a piece of floating cotton with sharp outlines and a flat base. qThe base appears white to light gray, and, on a humid day, may be only a few thousand feet above the ground and a half a mile or so wide. qThe top of the cloud— often in the form of rounded towers—denotes the limit of rising air and is usually not very high. qThese clouds can be distinguished from stratocumulus by the fact that cumulus clouds are detached (usually a great deal of blue sky between each cloud) whereas stratocumulus usually occur in groups or patches. qcumulus has a dome- or tower-shaped top as opposed to the generally flat tops of the stratocumulus. qCumulus clouds that show only slight vertical growth (cumulus humilis) are associated with fair weather; therefore, we call these clouds “fair weather cumulus.” qIf the cumulus clouds are small and appear as broken fragments of a cloud with ragged edges, they are called cumulus fractus.  Harmless-looking cumulus often CUMULUS CONGESTUS develop on warm summer mornings and, by afternoon, become much larger and more vertically developed. When the growing cumulus resembles a head of cauliflower, it becomes a cumulus congestus, or towering cumulus. Most often, it is a single large cloud, but, occasionally, several grow into each other, forming a line of towering clouds, as shown. Precipitation that falls from a cumulus congestus is always showery.  CUMULONIMBUS If a cumulus congestus continues to grow vertically, it develops into a giant cumulonimbus—a thunderstorm cloud. While its dark base may be no more than 2000 ft above the earth’s surface, its top may extend upward to the tropopause, over 35,000 ft higher. can occur as an isolated cloud or as part of a line or “wall” of clouds.  Tremendous amounts of energy are released by the condensation of water vapor within a cumulonimbus and result in the development of violent up- and downdrafts, which may exceed fifty knots. The lower (warmer) part of the cloud is usually composed of only water droplets. Higher up in the cloud, water droplets and ice crystals both abound, while, toward the cold top, there are only ice crystals. Swift winds at these higher altitudes can reshape the top of the cloud into a huge flattened anvil. These great thunderheads may contain all forms of precipitation—large raindrops, snowflakes, snow pellets, and sometimes hailstones—all of which can fall to earth in the form of heavy showers. Lightning, thunder, and even violent tornadoes are associated with the cumulonimbus Some Unusual Clouds  Harmless-looking cumulus often develop on warm summer mornings and, by afternoon, become much larger and more vertically developed. When the growing cumulus resembles a head of cauliflower, it becomes a cumulus congestus,or towering cumulus. Most often, it is a single large cloud, but, occasionally, several grow into each other, forming a line of towering clouds, as shown. Precipitation that falls from a cumulus congestus is always showery.