Convection, Conduction, and Radiation

• Conduction


  The transfer of thermal energy through a substance, or between substances in contact, by the collision of particles
• Convection


  The transfer of thermal energy from one part of a fluid to another by circulating current of faster and slower moving particles
• Radiation


  The transfer of radiant energy using electromagnetic waves
• Geothermal Energy


  Energy contained below earth's surface
• Radiant energy


  Energy that travels in the form of electromagnetic waves through space; including visible light, ultraviolet rays, and infrared rays
• Igneous rock


  Rock formed from magma that has cooled and solidified
• Metamorphic rock


  Rock that is formed when heat and pressure change existing rock
• Particle theory of matter


  An explanation of what matter is made of and how it behaves
• All matter is made up of tiny particles
• Particles have empty spaces in between them
• Even though you cannot see them particles are moving randomly all the time
• Particles move faster and spread farther apart when they are heated
• Particles attract each other so they tend to stay together rather than fly apart
• Radiation


  • Radiant energy travels outward in front the sun through empty spaces
  • They travel in the form of electromagnetic waves or rays
  • The sun emits electromagnetic rays in all directions but only a small portion of them reach Earth
  • The energy given off by objects that emit infrared rays is converted to thermal energy in your skin which is why they feel hot
  • Most radiant energy from the sun that reaches Earth's surface is in the form of visible light and infrared rays
• Absorption of radiant energy

  • The color and texture of objects affect how much energy is absorbed
  • Darker colors absorb radiant energy better than lighter or shiny surfaces
• Convection


  • Convection does not occur in a solid because the particles of a solid only vibrate they cannot flow
  • In substances such as water thermal energy can be transferred from one area to another
  • The continuous movement of warmer and colder soup in a pot is an example of convection
  • There are a lot of examples of convection in the environment
• Conduction


  • Cooking an egg in a pan on a stove is an example of conduction
  • The thermal energy transfers from the hot stove burner and through the pan
  • The particles in the hot stove burner vibrate quickly
  • Conduction is caused by the collision of particles
  • The pots and pans we use for cooking conduct energy soon from a hot burner to cold food
• Conductors


  A substance or material that allows electricity to flow through it (Examples: copper and aluminum)
• Insulators


  Insulators transfer less energy than some other objects (foam, fleece,felt, wood,plastic, and rubber)
• Geothermal energy


  • Energy contained below earth's surface
  • Geothermal energy causes earthquakes, hot springs, and geysers
  • Geothermal energy can affect the rocks inside the earth
  • It can melt them or change them into different types of rocks
• Magma


  Molten rock
• Earth's crust is always moving, it moves very slowly
• Sometimes two pieces of the earth's crust push into each other, this can push rocks from the surface toward the hot core
• Diamond


  • The hardest mineral on earth
  • Diamonds are metamorphic rocks
• Igneous rock


  • When magma cools, it becomes a solid again, a rock formed from cooled magma is an igneous rock
  • When lava cools it becomes a solid rock, these new rocks are igneous
• Metamorphic rock


  Metamorphic rocks are formed when heat and pressure change existing rock
• Diamonds form from a mineral called graphite
• The high heat and pressure in Earth's crust change graphite into diamond
• Convection and its relation to weather

  • Large convection currents in the air are called "wind"
  • The warm air particles above the land are more strongly heated by the warm land surface below
  • The cool, dense air above the water moves down and toward the land
  • The warm air that rises high into the atmosphere over the land eventually moves over the water, cools down, sinks, and then moves toward the land again
  • Thunderstorms often form on hot humid days
• Convection and Earth's mantle

  • Earth's surface is warmed by energy from the sun
  • The energy is then transferred to the air above the surface of the ground by conduction
  • As convection pushes the air higher, the water vapor cools and condenses into microscopic droplets of water that appear as white puffy clouds
  • The temperature of Earth's mantle increases as you go deeper
  • Over millions of years, cooler mantle rocks sink as warmer mantle rock rises closer to Earth's crust
  • These convection currents transfer energy and many cause volcanic eruptions
• Insulation in buildings


  • Fur, wool, and down keep animals warm
  • Air is not very good at transferring energy by conduction or convection
  • A green roof system has a waterproof barrier, drainage, a lightweight groth medium that acts like soil and vegetation
  • Any gaps in the thermal envelope of a house should be sealed
  • Moving air is a serious cause of energy loss in a home
  • A negative side from having your house tightly sealed is any moisture inside the house from people breathing, cooking, and taking showers is trapped
  • In a heat exchanger the air ducts carrying the saddle indoor air are in close contact with the ducts carrying the fresh outside air
  • To prevent unwanted energy transfer, homebuilders sometimes install a shiny radiant barrier in the attic
  • Radiant barriers can also be applied to air ducts and water pipes to prevent energy loss as warm air and hot water travel throughout the house
• One way to reduce heating and cooling costs is to replace older windows with low-E window