geo notes

• Satellite images


  Images of the Earth's surface taken by satellites orbiting the planet
• Satellite image creation


  1. Satellites have sensors (cameras) that constantly take images of the Earth

  2. Sensors send digital images back to computers on Earth's surface

  3. Computers process the images to produce different information about the Earth's surface
• Information from satellite images

  • Water (areas with too much or too little)
  • Vegetation (plant growth, greenery)
  • Land use (informal settlements, urban growth)
  • Cloud patterns (weather forecasts, climatic conditions)
• Landsat 7 satellite


  • Launched by the United States in 1998 to provide South Africa with daily images of the Earth's surface
• Using satellite images


  1. Satellite in orbit takes images of the same place daily

  2. Images are processed on a Geographic Information System (GIS) on a computer

  3. Different images can be compared to gather information about a specific area
• Benefits of satellite images


  • Don't need to go to specific area to gather information
  • Can provide information about vegetation, water, storms, pollution, soil quality, crops, weather, animal migration, population estimates, etc.
• Satellite images use different colours and shades to identify things easily
• Black areas show water, dark areas show mountains, other shades show settlement and vegetation
• The purpose of satellite technology is to constantly take images of the Earth's surface
• Latitude


  Distance from the equator
• Latitude


  • At the equator, the sun's rays fall vertically to the earth's surface. These have less atmosphere to pass through and less land to heat. The heat is therefore very intense.
  • As one moves away from the equator, the sun's rays are spread out more. The rays have more atmosphere to pass through and more land to heat. The heat is therefore less intense.
  • Temperature decreases as one moves away from the equator
• Rainfall and latitude


  • Temperatures are higher near the equator. This heat causes more evaporation (water changes to water vapour). Water vapour then condenses onto solid particles, forming clouds (condensation). Clouds release precipitation in the form of rain.
  • As one moves from the equator towards the north and south poles, it becomes colder. There is therefore less evaporation, condensation and precipitation.
• Temperature range


  The difference between the hottest and coldest temperature at any place
• Distance from the sea

  • In summer, inland regions heat up much faster than coastal waters do (land heats up quicker than water).
  • Cool winds blow from the ocean onto the coast, therefore cooling temperatures of coastal regions. Inland regions don't have cool winds to lower temperatures.
  • In winter, the ocean cools much more slowly than the land (inland regions). Warmer winds therefore blow from the ocean onto the land raising the temperature of coastal regions. Inland regions don't have warmer winds to raise their temperature.
  • Inland regions have a large temperature range with hot summers and cold winters. Coastal regions have a smaller temperature range with warm summers and moderate winters.
• Rainfall and distance from the sea


  Coastal regions experience more evaporation than inland regions do because there is a large mass of water in the form of the ocean at the coast. Coastal regions therefore experience more rainfall than inland regions do.
• Altitude


  The higher you go, the colder it gets. The air gets thinner and drier.
• Temperature and altitude


  • Bloemfontein (1400m above sea level) has a mean temperature of 16.1°C, while Durban (5m above sea level) has a mean temperature of 26.6°C.
• Altitude and rainfall


  • Altitude assists in the process of condensation. Air containing water vapour rises (above sea level) and cools resulting in condensation, causing clouds to form. Clouds can release rainfall.
• Ocean currents


  An ocean current is like a river within the ocean that flows from one place to another. Ocean currents occur because water at the equator is warmer than at the North and South Poles. Different water temperatures cause water to circulate, which results in a current.
• Coastal regions experience more rainfall than inland regions
• The higher you go, the colder it gets
• The air gets thinner and drier as you go higher in altitude
• Altitude


  Height above sea level
• Bloemfontein is high up and has a lower temperature than Durban
• Mountains are always a lot colder and can be covered in snow
• Mount Kilimanjaro in Kenya is only 3 degrees of the equator yet is freezing cold due to the effects of altitude
• How altitude affects rainfall


  1. Air containing water vapour rises (above sea level) and cools resulting in condensation causing clouds to form

  2. Clouds can release rainfall
• A place's altitude will not necessarily affect the amount of rainfall it will have
• Ocean current


  A river within the ocean that flows from one place to another
• Ocean currents occur because water at the equator is warmer than at the North and South Poles
• Warm currents flow from the equator


  Cold currents flow from the North and South Poles
• A warm ocean current


  Warm air above it, increases temperature of air above land
• A cold ocean current


  Cold air above it, decreases temperature of air above land
• Warm moist air from a warm ocean current

  Higher levels of evaporation and condensation causing more rainfall
• Cool dry air from a cold ocean current


  Lower levels of evaporation and condensation causing less rainfall
• It is colder at the top of a mountain than the bottom


  Temperature decreases with altitude/height
• Places facing the sun for long periods

  Have higher temperatures
• Places blocked from the sun by mountains

  Have cooler temperatures
• How mountains affect rainfall


  1. Warm moist air blows over the ocean and meets with a mountain

  2. The mountain forces the warm moist air to rise

  3. Warm moist air cools as it rises

  4. Condensation occurs forming a cloud

  5. Rain occurs on the wet windward side of the mountain

  6. There is dry air on the dry leeward side of the mountain
• South Africa lies between the 22°S and 35°S lines of latitude and between the 17°E and 33°E lines of longitude