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Geography Class

The Impact of Temperature on the Landscape

    1. Global temperature patterns leave a mark on the landscape.
      1. Many physical features are affected by local temperature conditions.
    2. Long-run temperature conditions affect the organic and inorganic components of the landscape.
      1. Animals and plants often evolve in response to hot or cold climates.
      2. Soil development is affected by temperature, with repeated fluctuations in temperature being the primary cause of the breakdown of exposed bedrock.

Energy, Heat, and Temperature

    1. Energy—the capacity to do work (can take on various forms) or anything that changes the state or condition of matter.
      1. Forms of energy include kinetic energychemical energy, and radiant energy.
      2. Energy occurs at the micro scale, causing the motion of atoms and molecules.
        1. Molecules in all substances possess kinetic energy—the energy of movement.
        2. The greater the amount of energy added to a substance, the greater the kinetic energy.
      3. Work—force acting over distance
        1. When a force is involved in moving matter around, energy has been transferred from one form to another.
      4. Power—energy being transferred per unit of time
      5. Internal Energy—energy at the atomic or molecular level
        1. All substances comprise moving atoms.
        2. Matter’s state depends on how fast the atoms are moving.
        3. Because of this constant movement, the molecules of all substances possess energy.
        4. This is kinetic energy.
      6. Temperature and Heat
        1. Temperature is a description of the average kinetic energy of the molecules in a substance.
        2. Heat (also known as thermal energy) is the energy that transfers from one substance to another because of temperature differences.
          1. Heat is simply energy transferred from an object with a higher temperature to an object with a lower temperature.
            • This decreases the internal energy of the hotter object and increases the internal energy of the cooler one.
          2. Internal energy of substances can be changed to other forms, such as work.
        3. Measuring Temperature
          1. There are a number of instruments for measuring temperature, including thermometers. All work on the principle that most substances expand when heated, calibrating this change in volume to measure temperature.
          2. There are three temperature scales used in the United States: the Fahrenheit scale, the Celsius scale, and the Kelvin scale.
          3. Fahrenheit Scale—used by public weather reports from the National Weather Service and the news media; few countries other than the United States use it.
          4. Celsius Scale—used either exclusively or predominately in most countries other than the United States, which uses it for scientific work. It is slowly being established to supersede the Fahrenheit scale.
            1. Celsius to Fahrenheit: degrees Fahrenheit = (degrees Celsius × 1.8) + 32°
            2. Fahrenheit to Celsius: degrees Celsius = (degrees Fahrenheit − 32°) /1.8
          5. Kelvin Scale—used in scientific research, but not by climatologists and meteorologists.
            1. Measures what are called absolute temperatures.
              • Degrees Celsius = degrees Kelvin – 273°
              • Degrees Kelvin = degrees Celsius + 273°

Solar Energy

        1. The Sun is the only significant source of energy for Earth’s atmosphere.
          1. Solar energy consists of electromagnetic waves, which do not diminish in intensity despite traveling 150 million kilometers (93 million miles) to Earth.
          2. Energy travels at the speed of light, so sunlight takes 8 minutes to reach Earth.
        2. Radioactive decay within Earth and tidal energy are of minor importance.
          1. Elements such as uranium, thorium, and potassium
        3. Electromagnetic Radiation
          1. Wavelength is measured by the distance of a crest of one wave to the crest of the next.
            1. Electromagnetic Spectrum—consists of waves of various lengths; only three areas of the spectrum are important to the study of physical geography:
              • Visible light—0.4 to 0.7 micrometers; makes up only 3 percent of the entire electromagnetic spectrum but composes a large portion of solar energy.
              • Ultraviolet radiation—0.01 to 0.4 micrometers; too short to be seen by the human eye; could cause considerable damage to living organisms if the shortest waves reached Earth’s surface, but the atmosphere filters them out.
              • Infrared radiation—0.7 to 1000 micrometers; too long to be seen by the human eye; emitted by hot objects and sometimes called “heat rays”; radiation emitted by Earth is entirely infrared (sometimes called thermal infrared), but this composes only a small fraction of solar radiation.
              • Shortwave versus Longwave Radiation—almost completely in the form of visible light, ultraviolet, and short infrared radiation (collectively referred to as shortwave radiation). Radiation emitted by Earth is entirely within the thermal infrared portion of the spectrum (also known as longwave radiation).
                • A wavelength of 4 micrometers is generally accepted as the boundary between shortwave and longwave radiation.

Basic Warming and Cooling Processes in the Atmosphere

To understand how energy travels from the Sun to Earth, it’s best to examine how heat energy moves.

    1. Heat energy moves from one place to another in three ways:
      1. Radiation
      2. Conduction
      3. Convection
    2. Radiation
      1. Radiation—process by which electromagnetic energy is emitted from an object; radiant energy flows out of all bodies, with the temperature and nature of the surface of the objects playing a key role in radiation’s effectiveness.
        1. Hot bodies are more potent than cool bodies (and the hotter the object, the more intense the radiation and the shorter the wavelength).
        2. Blackbody radiator—a body that emits the maximum amount of radiation possible, at every wavelength, for its temperature.
        3. Earth emits longer wavelengths of radiant (i.e., thermal infrared) energy.
      2. Absorption
        1. Absorption—the ability of an object to assimilate energy from the electromagnetic waves that strike it.
          1. Different objects vary in their capability to absorb radiant energy (and thus increase in temperature).
            • Color plays a key role in an object’s absorption ability; dark-colored surfaces absorb the visible portion of the electromagnetic spectrum more efficiently than light-colored surfaces.
          2. Reflection
            1. Reflection—the ability of an object to repel waves without altering either the object or the waves.
            2. Albedo—the overall reflectivity of an object or surface.
          3. Scattering
            1. Scattering—the process by which light waves change in direction, but not in wavelength. Occurs in the atmosphere when particulate matter and gas molecules deflect wavelengths and redirect them in many directions.
              1. Sometimes when insolation is scattered, the waves are diverted into space, but most continue through the atmosphere in altered, random directions.
              2. Amount of scattering depends on length of the wave and the size, shape, and composition of the molecule or particulate.
                • Why is the sky blue?
                  • Rayleigh scattering causes shorter wavelengths of visible light to be scattered.
                  • Violets and blues in the visible part of the spectrum are shorter in wavelength than the oranges and reds. Shorter waves like violets and blues are more readily scattered by the gases in the atmosphere, so they are more likely to be redirected.
                  • The Sun appears reddish at sunrise and sunset because the path of light through the atmosphere is longer, so most of the blue light is scattered before the light waves reach Earth’s surface.
                • When the atmosphere contains large quantities of larger particles, such as suspended aerosols, all wavelengths of visible light are more equally scattered.
                  • In such instances, the sky has a gray appearance.
                  • This process is called Mie scattering.

Earth’s Solar Radiation Budget

Why doesn’t Earth get progressively warmer or cooler?

      1. Long-Term Energy Balance
        1. In the long run, there is an apparent balance between the total amount of insolation received by Earth and the total amount of terrestrial radiation returned to space.
          1. However, a closer look shows that the atmosphere experiences a net gain of 14 units every year in terms of its annual balance, which is the result of longwave radiation being trapped in the atmosphere by greenhouse gases. Without it, Earth would not store the heat necessary for life.
        2. Outgoing energy from Earth also depends on the transport of latent heat from the process of evaporation. There is more water than land, so more than three-fourths of sunshine hits water, which evaporates moisture from bodies of water.
        3. Ultimately, atmospheric heating is a complicated sequence that has many ramifications:
          1. The atmosphere is heated mostly from below than from above.
          2. There is an environment of almost constant convective activity and vertical mixing.
        4. Albedo—ability of an object to reflect radiation; in the case of Earth, it relates to the amount of solar radiation or insolation that Earth scatters, or reflects back, into space.
        5. Earth’s Energy Budget—per Figure 4-18, Earth’s radiation budget is as follows:
          1. Insolation absorbed (in units):
            1. Ozone; 3, absorbed directly by the atmosphere; 21, absorbed by Earth’s surface: 45
              • 3 + 21 + 45 = 69
            2. Insolation reflected (in units):
              1. Atmospheric and surface reflection: 31
            3. Total energy budget: 69 + 31 = 100
            4. Energy budget surface and atmospheric processes associated with the greenhouse effect (in units):
              1. Lost from Earth’s surface via conduction and convection: 4
              2. Lost via evaporation: 19
                • 4 + 19 = 23
              3. Lost from Earth’s surface as longwave radiation: 110; lost from atmosphere back to Earth’s surface: 96
                • 110 – 96 = 14
              4. Lost from Earth’s surface as direct radiation directly back to space (in units): 8
              5. Surface longwave budget: 23 + 14 + 8 = 45
              6. Atmospheric longwave budget (in units):
                1. Longwave energy reradiated by ozone: 3
                2. Longwave energy reradiated by the atmosphere: 21
                  • 21 + 3 = 24
                3. Total reradiated surface and atmospheric longwave energy (in units):
                  1. 45 + 24 = 69
                4. Total longwave reradiated: 69; total shortwave reflected: 31
                  1. 69 + 31 = 100

Variations in Insolation by Latitude and Season

Earth does not evenly distribute heat through time and space; instead, there are variations in its radiation budget that relate to latitudinal and seasonal variations in how much energy is received by Earth.

        1. These imbalances are among the fundamental causes of weather and climate variations because they cause unequal heating of Earth and its atmosphere.
      • Latitudinal and Seasonal Differences
        1. There is unequal heating of different latitudinal zones for four basic reasons: angle of incidence, day length, atmospheric obstruction, and latitudinal radiation balance.
        2. Angle of Incidence—the angle at which rays from the Sun strike Earth’s surface; always changes because Earth is a sphere and because Earth rotates on own axis and revolves around the Sun.
          1. Angle of incidence is the primary determinant of the intensity of solar radiation received on Earth.
            • Heating is more effective the closer to 90° because the more perpendicular the ray, the smaller the surface area being heated by a given amount of insolation.
              • Angle is 90° if the Sun is directly overhead.
              • Angle is less than 90° if the ray is striking the surface at a glance.
              • Angle is 0° for a ray striking Earth at either pole.

Land and Water Temperature Contrasts

    1. Different kinds of surfaces react differently to solar energy, and surface characteristics play a major role in how Earth’s surface affects the heating of the air above it.
      1. There are almost limitless kinds of surfaces on Earth, both natural and human-made. Each varies in its receptivity to insolation, which in turn affects the temperature of overlying air.
    2. Warming of Land and Water
      1. Most significant contrasts occur between land and water surfaces.
      2. Heating: generally, in comparison to water, land heats and cools faster and to a greater degree.
        1. There are four main reasons why water and land are different:
          • Specific heat—the amount of energy it takes to raise the temperature of 1 gram of a substance by 1°C. Water’s specific heat is about five times as great as that of land, so it takes about five times more energy to increase its temperature.
          • Transmission—water is a better transmitter than land (because it’s transparent, whereas land is opaque). Heat diffuses over a much greater volume (and deeper) in water and reaches considerably lower maximum temperatures than on land.
          • Mobility—water’s mobility disperses heat both broadly and deeply; on land, heat can be dispersed only by conduction, and land is a very poor conductor.
          • Evaporative cooling—water has more moisture, so more potential for evaporation and losing heat; the cooling effect of evaporation slows down any heat buildup on the surface of a body of water.
        2. Cooling of Land and Water—water surface cools more slowly and to a higher temperature compared with land for one main reason:
          1. Heat in water is stored deeply and brought to the surface only slowly.
            1. A circular pattern is created so that the entire body of water must be cooled before the surface temperature decreases significantly.
          2. Implications—oceans create more moderate climates for maritime areas, so that interiors of continents hold the hottest and coldest places on Earth.
            1. Distinction between continental and maritime climates is the most important geographic relationship in the study of atmosphere.
            2. Oceans provide a sort of global thermostatically controlled heat source, moderating temperature extremes.
            3. Differences Between Hemispheres
              • Northern Hemisphere has greater extremes in average annual temperature range because it is the land hemisphere—39 percent of its area is land surface.
              • Southern Hemisphere is the water hemisphere—only 19 percent of its area is land.

Mechanisms of Global Energy Transfer

  1. The tropics would become progressively warmer (and less habitable) until the amount of heat energy absorbed equaled the amount radiated from Earth’s surface if not for two specific mechanisms moving heat poleward in both hemispheres:
    1. Atmospheric Circulation—the most important mechanism, accomplishing 75 to 80 percent of all horizontal heat transfer.
    2. Oceanic Circulation—ocean currents reflect average wind conditions over a period of several years.
      • Current—various kinds of oceanic water movements.
      • Atmosphere and ocean serve as thermal engines; their currents are driven by the latitudinal imbalance of heat.
        • There is a direct relationship between these two mechanisms:
          • Air blowing over an ocean is the principal driving force of major surface ocean currents.
          • Heat energy stored by oceans affects atmospheric circulation.
  1. The Basic Pattern—all Earth’s five ocean basins are interconnected:
    • North Pacific
    • South Pacific
    • North Atlantic
    • South Atlantic
    • South Indian
      • All the basins have a single simple pattern of surface currents:
        • Basically, warm tropical water flows poleward along the western edge of each ocean basin, and cool high-latitude water flows equatorward along the eastern margin of each basin.
        • This pattern is impelled by the wind and caused by the Coriolis effect, the deflective force of Earth’s rotation.
  1. Equatorial Counter-Currents
    1. West-to-east flows occur approximately along the equator
      • These are fed by equatorial currents near the western margin of each ocean basin.
      • The equatorial counter-currents drift poleward and then descend and feed the equatorial currents near the eastern ends of their paths.
  1. Northern and Southern Variations
    1. In the Northern Hemisphere, the bulk of the current flow from the North Pacific and North Atlantic is prevented from entering the Arctic Ocean because the continents are close together.
      • Flow is more limited in the North Pacific because Asia and North America are very close together.
    2. In the Southern Hemisphere, distance between continents permits continuous flow around the world.
      • West Wind Drift—circumpolar flow around latitude 60° S.
  2. Current Temperatures
        1. Low-latitude currents (equatorial current, equatorial counter-current) have warm water.
        2. Poleward-moving currents on the western sides of ocean basins carry warm water toward higher latitudes.
        3. High-latitude currents in the Northern Hemisphere gyres carry warm water toward the east, and high-latitude currents associated with the Southern Hemisphere gyres (generally combined into the West Wind Drift) carry cool water to the east.
        4. Equatorward-moving currents on the eastern sides of ocean basins carry cool water toward the equator.
  3. Western Intensification

The poleward-moving warm currents off the east coasts of continents tend to be narrower, deeper, and faster than the equatorward-moving cool currents flowing off the west coasts of continents.

        • This phenomenon is called western intensification because it occurs on the western side of the subtropical gyres.
        • Western intensification arises for a number of reasons.
          • The Coriolis effect is great a factor.


          1. The northwestern portions of the Northern Hemisphere ocean basins receive an influx of cool water from the Arctic Ocean.
            1. Wherever an equatorward-flowing cool current pulls away from a subtropical western coast, a pronounced and persistent upwelling of cold water occurs.
            2. There is a deep ocean circulation pattern—sometimes called the global conveyor belt circulation—that influences global climate in subtle, but nonetheless important, ways.

Vertical Temperature Patterns

    1. Environmental Lapse Rate
      1. Rate at which temperature drops as altitude increases can vary according to season, time of day, amount of cloud cover, and other factors.
    2. Average Lapse Rate
      1. Normal vertical temperature gradient, with temperature dropping 6.5°C per kilometer (3.6°F per 1000 feet).
    3. Temperature Inversions
      • Prominent exception to average lapse rate, in which temperature increases with increasing altitude.
        • Common but usually brief and only to a restricted depth.
        • Affect weather by cutting the possibility of precipitation and creating stagnant air conditions.
      • Surface Inversions—there are three kinds of surface inversions:
        • Radiational inversions—surface inversions that result from rapid radiational cooling of lower air, typically on cold winter nights (and thus in high latitudes).
        • Advectional inversions—surface inversions caused by a horizontal inflow of colder air into an area (such as cool maritime air blowing onto a coast); usually short-lived and shallow, and can occur any time of year, but are more common in winter than in summer.
        • Cold-air-drainage inversions—surface inversions caused by cooler air sliding down a slope into a valley; fairly common during winter in some midlatitude regions.
      • Upper-Air Inversions
      • Also known as subsidence inversions—temperature inversions that occur well above Earth’s surface as a result of air sinking from above.
    • Global Temperature Patterns


    • An individual map can only reveal so much.
      • Maps of global temperature patterns display seasonal extremes, not annual averages.
        • January and July are chosen because, for most places on Earth, they are the months with the lowest and highest temperatures.
        • Temperature maps are based on monthly averages, which use daily averages (not maximum daytime heating or maximum nighttime cooling).
      • Viewed correctly, they permit a broad understanding of Earth’s temperature patterns.
      • Isotherm—a line joining points of equal temperature.
    • Prominent Controls of Temperature
      • Four factors control gross patterns of temperature: altitude, latitude, land-water contrasts, and ocean currents:
        • Latitude—if Earth had a uniform surface and did not rotate, the isotherms would probably coincide with parallels (with temperature progressively decreasing poleward from the equator).
          • Latitude is the primary governor of insolation, the fundamental cause of temperature variation over the world.
        • Altitude—most maps displaying world temperature patterns adjust for altitude by reducing temperature to what it would be if the station giving temperature were at sea level.
          • Use average lapse rate to convert to sea-level temperature.
          • Must realize that while these maps are useful for showing world patterns, they do not indicate actual temperatures for locations not at sea level.
        • Land-Water Contrasts—continents have higher summer temperatures than do oceans.
          • Likewise, continents have lower winter temperatures than do oceans.
        • Ocean Currents—because of land-water heating contrasts, cool currents deflect isotherms equatorward, whereas warm currents deflect them poleward.
      • Map shows how isotherms have a general east-west trend, in conjunction with the influence of latitude, which shows that temperatures tend to correspond with latitude, with warmer temperatures toward the equator and cooler temperatures toward the poles.
    • Seasonal Patterns
      • Between summer and winter, there is a latitudinal shift of isotherms: they move northward from January to July and return southward from July to January.
        • This latitudinal shift is much more pronounced in high latitudes than in low, and much more pronounced over continents than over oceans.
      • Temperature gradient, or the rate of temperature with horizontal distance, is steeper in winter than in summer, and steeper over continents than over oceans.
      • Colder Winter Locations
        • Coldest places on Earth: landmasses at higher latitudes.
        • In July in Antarctica.
        • In January in subarctic portions of Siberia, Canada, and Greenland.
      • Hottest Summer Locations
        • Hottest places on Earth: subtropical latitudes, where clear skies do not give the protection that clouds give in the tropics.
        • In July in northern Africa and southwestern portions of Asia and North America.
        • In January in subtropical parts of Australia, southern Africa, and South America.
      • Highest average annual temperatures: in equatorial regions, because they do not have winter cooling.
    • Annual Temperature Range
      • Maps showing average annual temperature range, which is the difference between the average temperatures of the warmest and coldest months.
      • Interiors of high-latitude continents and continental areas in general have much greater ranges than do equivalent oceanic latitudes.
      • Tropics have only slight average temperature fluctuations.
      • Differences Between Hemispheres
        • Northern Hemisphere has greater extremes in average annual temperature range because it is the land hemisphere—39 percent of its area is land surface.
        • Southern Hemisphere is the water hemisphere—only 19 percent of its area is land.
      • Measuring Global Temperatures
        • In recent years, scientists have used the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua and Terra satellites to gather global temperature data.
        • The “skin” temperature of ocean and land surfaces can be estimated through the measurement of emitted thermal infrared radiation.
        • Sea Surface Temperature (SST)
          • Influences the temperature of air masses over oceans and the intensity of storms.
          • Regular monitoring of SSTs aids in predicting El Niño events and provides info on long-term changes to Earth’s environment.
        • Land Temperature
          • Satellite-derived measurements provide surface temperature measurements.

Climate Change and Global Warming

    1. Air temperature increases when certain atmosphere gases (such as carbon dioxide, methane, and nitrous oxide) inhibit the escape of longwave terrestrial radiation. It is a naturally occurring process; without it, Earth would be a frozen mass. Now, however, there are strong indications that this effect has been intensified by human actions.
    2. Temperature Change Over the Last Century
      1. According to data, the average global temperature increased more than 0.7°C during the twentieth century.
      2. Temperatures increased 0.2°–0.3°C during the last quarter of the twentieth century alone.
      3. Temperature change over the past 100 years is greater than in any other century in at least the last 1000 years.
      4. Measurements of this temperature increase, both direct and proxy, have pointed toward a clear warming trend on Earth in recent decades.
    3. Although climate changes do occur naturally, the evidence is increasingly pointing to these changes being caused by anthropogenic sources.
      1. This increase in carbon dioxide is attributed to the increased burning of fossil fuels in recent decades.
    4. Increasing Greenhouse Gas Concentrations
      1. Carbon dioxide and other greenhouse gases seem to be the principal offenders.
      2. Carbon dioxide is believed to be responsible for about 64 percent of the human-enhanced greenhouse effect.
      3. Since 1750, carbon dioxide levels have increased by more than 40 percent.
      4. The latest paleoclimatological data indicate that the current concentration of carbon dioxide in the atmosphere of 401 parts per million is greater than at any time in the past 800,000 years.
        1. The current rate of increase is greater than at any time in the past 20 millennia.
      5. The increased use of other gases—methane, chlorofluorocarbons, and nitrous oxides—have also contributed to the increase in global temperatures.
      6. These increases correlate with the average increase in global temperature.
    5. The warming has not been globally uniform, but rather widespread.
      1. Because of the complexity of feedback loops in climate systems, predictions regarding global warming are difficult to formulate.
    6. Computer modeling shows that if the trend continues, heat and drought would become more prevalent in much of the midlatitudes, and milder temperatures would prevail in the higher latitudes. Arid lands might receive more rainfall. Ice caps would melt and global sea levels would rise. Current living patterns would have to change over much of the world.
    7. Intergovernmental Panel on Climate Change (IPCC)
    8. The Intergovernmental Panel on Climate Change (IPCC) released its Fourth Assessment Report in 2007, discussing climatic changes on both global and local scales and the strong evidence pointing to this change being a result of human activities
      1. According to the IPCC report:
          1. Warming of the climate system is unequivocal, as exhibited by increases in Earth’s air and surface temperatures, widespread melting of snow and ice, and rising average global sea level.
          2. These changes have a 90 percent probability of being anthropogenic in nature and are strongly correlated with increased greenhouse gas emissions.
          3. Overall, it is estimated that Earth’s climate system has changed on both a global and regional scale since the preindustrial era, and there is evidence that the warming observed over the past 50 years is a result of human activities.
      1. The report is available at

Energy for the 21st Century: Solar Power

  1. During a 24-hour day, an average of 164 Watts per square meter shines on Earth’s surface, providing more than enough energy to meet the electrical generation needs of all humans on Earth.
    1. Overall, about 0.1 percent of global energy is provided via solar power, with the world’s photovoltaic capacity reaching 15 gigawatts in 2008 and approximately 177 gigawatts in 2014.
  2. Photovoltaic cells are traditionally constructed of inorganic materials such as silicon, with other materials added to increase conductivity.
    1. When photons (particles of light) strike the silicon cell’s surface, some of the electrons are displaced from the circuit’s negative layer and are forced to flow into the cell’s positive layer.
      1. The flow of these electrons creates an electrical current that can then be used as a power source.
    2. Using photovoltaics to generate electricity offers several advantages.
      1. A photovoltaic power plant has a low capital cost, and, once installed, requires little maintenance of the solar panels.
      2. No fuel or other energy sources, except for the Sun, are required to create the electricity.
      3. They have the potential to create decentralized energy electrical generation because individual pieces of equipment, or structures overall, do not have to be wired into a grid but instead can generate their own energy on site.
    3. Disadvantages of photovoltaic cells include:
      1. Low efficiency—Today’s photovoltaic cells are capable of capturing only a limited portion of the solar spectrum, with a sizable amount of the captured photon energy being lost as heat.
      2. Limited electrical generation capacity under cloudy and hazy conditions, and they generate no electricity when it is dark, so storage batteries must provide power during down hours.
    4. Geography of Solar Capacity
      1. Climate and latitude are the greatest limiting factors.
      2. Some countries with limited solar radiation have adopted policies that favor solar development.
        1. Germany and Italy have significantly increased their solar output.
      3. Scientists specializing in solar energy are investigating new technologies to boost the potential of photovoltaics as a viable electrical generation medium. Current methods include:
        1. The use of mirrors and lenses to better focus the Sun’s rays onto photovoltaic arrays.
        2. The development of multispectral photovoltaic cells that can capture a wider array of the electromagnetic spectrum, including infrared energy.
        3. The incorporation of organic elements that will allow photovoltaic capability to be integrated into thin, flexible, and, in some instances, even transparent materials.

Global Environmental Change: The Deadly Heat Waves of 2015

  1. Heat waves are the deadliest natural disaster on Earth, and developing countries are disproportionally affected.
  2. India experiences a heat wave annually before its monsoon season.
    1. High mountains to the northeast block cool air from higher latitudes.
    2. During the summer of 2015, monsoon season was delayed a week and a half because of El Niño.
      1. The late rainy season and temperatures as high as 48°C (120°F) made this the fifth deadliest heat wave on record globally, including 2500 deaths from mid-May to mid-June.
    3. Pakistan also suffered dramatic temperatures, as high as 49°C (120°F), by late June 2015.
      1. More than 2000 deaths occurred as a result of dehydration and heat stroke.
      2. Heat wave occurred during Ramadan, when Muslims refrain from both food and water during daylight hours.
      3. Widespread electrical grid failures made the situation worse.
    4. Subsiding, warming air of a massive high-pressure system lingered over the Persian Gulf for several days in July 2015.
      1. Affected United Arab Emirates, Qatar, Saudi Arabia, Kuwait, Iraq, and Iran.
    5. Temperature records were also broken in Germany, France, the Netherlands, the United Kingdom, Switzerland, and Japan.
    6. According to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, heat waves will increase in frequency, intensity, and geographic area in coming years.
      1. Heat-related deaths may triple by the 2050s.

 Measuring Earth’s Surface Temperature by Satellite

  1. In recent years, scientists have used the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua and Terra satellites to gather surface temperature data around the globe.
    1. Scientists can estimate the “skin” temperature of both land and ocean surfaces by measuring emitted thermal infrared radiation and using computer algorithms to compensate for absorption and scattering.
  2. Sea surface temperature (SST) influences both air mass temperature that originates over ocean areas and the intensity of storms (e.g., hurricanes).
    1. SST monitoring helps scientists anticipate the onset of El Niño events.
  3. Satellite-derived temperatures measure the temperature of the surface itself to produce land temperature measurements.
    1. High daytime surface temperatures in subtropical and midlatitude deserts in the Northern Hemisphere are a consequence of high sun and sparse cloud cover, but they cool significantly at night.

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Geog 001

1.  Introduction to Earth