Geography Study Materials and Hand-outs

In much of remote sensing,  the process  involves an interaction between incident radiation and the targets of interest. This is exemplified by the use of imaging systems where the following seven elements are involved. Note, however that remote sensing also involves the sensing of emitted energy and the use of non-imaging sensors.   1. Energy Source or Illumination (A)  - the first requirement for remote sensing is to have an energy source which illuminates or provides electromagnetic energy to the target of interest. 2. Radiation and the Atmosphere (B)  - as the energy travels from its source to the target, it will come in contact with and interact with the atmosphere it passes through. This interaction may take place a second time as the energy travels from the target to the sensor. 3. Interaction with the Target (C)  - once the energy makes its way to the target through the atmosphere, it interacts with the target depending on the properties of both...

Factors in Soil Formation 1.       Climate : The two most important climatic variables influencing soil formation are temperature and moisture.   ·          Temperature   has a direct influence on the   weathering   of bedrock to produce mineral particles. Rates of bedrock weathering generally increase with higher temperatures. Temperature also influences the activity of soil microorganisms, the frequency and magnitude of soil chemical reactions, and the rate of plant growth. ·          Moisture levels in most soils are primarily controlled by the addition of water via   precipitation   minus the losses due to evapotranspiration . High moisture availability in a soil promotes the weathering of bedrock and sediments, chemical reactions, and plant growth. The availability of moisture also has an influence on soil   pH   and the decompositi...

Geologic Time Geologists and geomorphologists describe the Earth's geologic history through a temporal system known as the  geologic time scale  . On this scale, time is measured using the following four units of time:  eons ,  eras ,  periods  and  epochs . All of these temporal subdivisions are established on the occurrence of some important geologic event. For example,  Hadean Eon  represents the time on Earth when life did not exist. During the  Archean Eon  life started and was dominated by one-celled  prokaryotic  life forms.  Eukaryotic  one-celled organisms became dominant in the  Proterozoic Eon . Multicellular organisms ruled the planet during the eon known as the  Phanerozoic . Table describes some of the important geologic events that have occurred since the Earth's formation some 4.6 billion years ago.   Table:  Geolog...

Perihelion and Aphelion According to Kepler's first law of planetary motion, all planets, comets, and asteroids in the Solar System have approximately elliptical orbits around the Sun. Hence, an orbiting body has a closest and a farthest point from its parent object, that is, a perihelion and an aphelion, known collectively as apsides. Orbital eccentricity measures the flatness (departure from a perfect circle) of the orbit. Perihelion The word "perihelion" stems from the Ancient Greek words "peri", meaning "near", and "helios", meaning "the Sun". The perihelion is the point in the orbit of a planet, minor planet, or comet, where it is nearest to its orbital focus, generally a star.   Aphelion "Aphelion" derives from the preposition "apo", meaning "away, off, apart". (The similar words "perigee" and "apogee" refer to the nearest and furthest points in some object's orbit around t...

  Earth's Size The size of Earth, like the size of all of the celestial bodies, is measured in a number of parameters including mass, volume, density; surface area, mean diameter, and circumference . Earth's Shape Earth's circumference and diameter differ because its shape is classified as an oblate spheroid or ellipsoid, instead of a true sphere. This means that instead of being of equal circumference in all areas, the poles are squished, resulting in a bulge at the equator, and thus a larger circumference and diameter there. The equatorial bulge at Earth's equator is measured at 26.5 miles (42.72 km) and is caused by the planet's rotation and gravity. Gravity itself causes planets and other celestial bodies to contract and form a sphere. This is because it pulls all the mass of an object as close to the center of gravity (the Earth's core in this case) as possible. Because Earth rotates, this sphere is distorted by the centrifugal force. This is the fo...