Earth's Energy and Heat Transfer

• The sun’s energy arrives on earth as electromagnetic radiation
• Visible light, infrared radiation, and ultraviolet radiation are the most common types

Visible Light

• A mix of all colors
• Red has the longest wavelength
• Violet has the shortest wavelength
• The sky is blue because the density and size of air molecules scatter blue wavelengths

Infrared Radiation

• Heat radiation
• Wavelengths are longer than visible light
• Makes up 49% of the sun's electromagnetic radiation

Ultraviolet Radiation

• Has short wavelengths and is not visible
• Can cause skin cancer, sunburn, and eye damage

Temperature

• Defined as the motions of molecules
• Faster movement of molecules indicates more energy and a higher temperature
• Radiation: Direct transfer of energy by electromagnetic waves

Conduction

• Requires direct contact between two objects
• Closer molecules make for better heat conductors

Convection

• Transfers heat through the movement of fluid
• Air is considered a fluid
• Uneven heating occurs because the Earth is tilted at 23.5%
• Materials heat up and cool down at different rates

Warm Air

• Less dense and rises
• Can hold more humidity
• A mass of warm air constitutes a low-pressure area

Cold Air

• Denser and sinks
• Holds less humidity
• A mass of cold air constitutes a high-pressure area
• Wind is created by temperature differences, leading to pressure differences
• Air moves from high-pressure (cold) to low-pressure (hot) areas, with cold air replacing rising warm air
• Wind: Horizontal movement from high to low pressure

Local Winds

• Result from unequal heating of the Earth's surface in a small area
• Sea breeze: Cool air from the ocean moves in to replace rising warm air over the land due to unequal heating of land and water
• Land breeze: Occurs when water is warmer than the land and is usually not as strong as a sea breeze

Global Winds

• Blow steadily from specific directions over long distances
• Caused by unequal heating of the Earth's surface and the Earth's rotation
• Coriolis effect: Air set in motion by pressure differences deflects to the right due to the Earth's spin (to the left in the southern hemisphere)

Jet Streams

• Fast-moving, high-altitude winds that influence air masses and storms
• The water cycle continually changes through condensation, precipitation, and evaporation

Evaporation

• Water changes from liquid to gas when more molecules leave the liquid state than return

Precipitation

• Solid or liquid water falling to Earth

Condensation

• Water changes from gas to liquid as water vapor leaves the air

Water in the Atmosphere

• Dew point: The temperature at which condensation occurs, air is saturated, and relative humidity is 100%
• Absolute Humidity: The amount of water vapor in the air
• Relative Humidity: The amount of water vapor in the air compared to the amount it could hold at that temperature
• Frost: Water vapor condenses as a solid
• Dew: Water vapor condenses as a liquid

Clouds

• Form when warm air rises and reaches the dew point, and moisture condenses on dust particles called condensation nuclei
• Classified by altitude and shape
  • Cirro-: Prefix meaning high level
  • Alto-: Prefix meaning middle level
  • Cumulus: Puffy
  • Stratus: Layered
  • Nimbo or Nimbus: Precipitation is falling

Rainbow

• Caused by refraction of sun rays passing through water droplets

Reflection

• The angle of incidence equals the angle of reflection

Refraction

• The angle of incidence and angle of refraction are not equal, so light is bent

Fog

• Cloud on the ground formed when the dew point equals the surface temperature

Rain

• Liquid water falling to Earth when air temperature is above 32 degrees

Snow

• Forms when cloud temperature is below 32 degrees and water vapor condenses into solid crystals

Hail

• Raindrops circulate up and down in a cumulonimbus cloud, freezing on the way up and gaining size

Sleet

• Raindrops freeze on their way down, passing through layers of colder air

Freezing Rain

• Rain falls to Earth and freezes upon hitting a cold surface