Page 126 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

4
concepts
kEy lEaRninG
Atmosphere and Surface Energy Balances
After reading the chapter, you should be able to:
• Define energy and heat, and explain four types of heat transfer: radiation, conduction, convection, and advection.
• Identify alternative pathways for solar energy on its way through the troposphere to Earth’s surface—transmission, scattering, refraction, and absorption—and review the concept of albedo (reflectivity).
• Analyze the effect of clouds and aerosols on atmospheric heating and cooling, and explain the greenhouse concept as it applies to Earth.
• Review the Earth–atmosphere energy balance and the patterns of global net radiation.
• Plot typical daily radiation and temperature curves for Earth’s surface— including the daily temperature lag.
• List typical urban heat island conditions and their causes, and contrast the microclimatology of urban areas with that of surrounding rural environments.
Designed and installed by Gardens in the Sky in June 2004, the green roof at the Robertson Building in downtown Toronto covers over 370 square metres—about half of the historic building’s roof—with more than 11 hardy perennials commonly found in Ontario. The roof helps mitigate the urban heat-island effect, an energy balance phenomenon that causes temperatures
in cities to be warmer than those of surrounding regions. This type of living roof provides insulation for the building below, reducing heating and cooling costs by as much as 20%. The roof also absorbs less insolation than one made of black asphalt, lessening the overall warming of city temperatures. Urban heat islands are one component of the Earth–atmosphere energy balance discussed in this chapter. [Terry McGlade, Flynn Canada.]