ESCI 1010 Weather and Climate
Chapter 3 Notes
Albedo
• Percentage of visible light reflected is termed albedo
• Light-colored surfaces (e.g., snow, light roofs) reflect more light
• Dark-colored surfaces (e.g., forests, dark roofs) absorb more light
• Planetary albedo = 30%
Blue Skies and Red Suns
• Short wavelengths of light scattered more effectively
• Sky is blue due to blue visible light being scattered toward the observer
• Red color of sunrises and sunsets due to increased scattering (i.e., there is more atmosphere to
travel through)
Crepuscular Rays
• Scattering of sunlight by haze, water droplets, or dust particles
Rainbows
• Visible light contains an array of colors we commonly call the “colors of the rainbow”
• Rainbow: luminous arc formed by the refraction and reflection of light in drops of water
Heat
• Specific heat: amount of energy required to raise the temperature of a given mass of substance
by a given amount
• Latent heat: energy required to change the phase of a substance
The Greenhouse Effect
• Earth’s surface temperature would be 0°F (-18°C) without the greenhouse effect
• Actual surface temperature is 59°F (15°C)
• “Greenhouse” term not quite accurate because a true greenhouse impedes the transfer of
latent and sensible heat by convection, but the atmosphere does not
Global Temperature Distribution
• One of the most immediate and obvious outcomes of radiation gain or loss is a change in the air
temperature
• Isotherms: lines of equal temperature
Temperature Controls
• Latitude
• Altitude
• Atmospheric circulation patterns
• Contrasts between land and water
• Warm and cold ocean currents
• Local conditions (microclimate)
o Slope orientation and steepness (e.g., south- vs. north-facing)
o Densely wooded areas vs. bare land
1
Chapter 3 Notes
Albedo
• Percentage of visible light reflected is termed albedo
• Light-colored surfaces (e.g., snow, light roofs) reflect more light
• Dark-colored surfaces (e.g., forests, dark roofs) absorb more light
• Planetary albedo = 30%
Blue Skies and Red Suns
• Short wavelengths of light scattered more effectively
• Sky is blue due to blue visible light being scattered toward the observer
• Red color of sunrises and sunsets due to increased scattering (i.e., there is more atmosphere to
travel through)
Crepuscular Rays
• Scattering of sunlight by haze, water droplets, or dust particles
Rainbows
• Visible light contains an array of colors we commonly call the “colors of the rainbow”
• Rainbow: luminous arc formed by the refraction and reflection of light in drops of water
Heat
• Specific heat: amount of energy required to raise the temperature of a given mass of substance
by a given amount
• Latent heat: energy required to change the phase of a substance
The Greenhouse Effect
• Earth’s surface temperature would be 0°F (-18°C) without the greenhouse effect
• Actual surface temperature is 59°F (15°C)
• “Greenhouse” term not quite accurate because a true greenhouse impedes the transfer of
latent and sensible heat by convection, but the atmosphere does not
Global Temperature Distribution
• One of the most immediate and obvious outcomes of radiation gain or loss is a change in the air
temperature
• Isotherms: lines of equal temperature
Temperature Controls
• Latitude
• Altitude
• Atmospheric circulation patterns
• Contrasts between land and water
• Warm and cold ocean currents
• Local conditions (microclimate)
o Slope orientation and steepness (e.g., south- vs. north-facing)
o Densely wooded areas vs. bare land
1
