中国地质大学武汉环境化学03Atmosphericradiationandparticle.ppt

Chapter three Climate: Radiation Balance Albedo: Particles and Clouds 1. Climate: Radiation Balance Weather and Climate Factors affecting the earth’s climate Solar irradiation: Solar constant Radiation Budget Albedo The incoming solar energy per unit area at the earth’s surface Spectral distribution of solar and terrestrial radiation Balancing incoming and outgoing energy for the Earth-Atmosphere system Weather and Climate Weather is the condition of the atmosphere in terms of temperature, humidity, winds and precipitation. Climate is defined as the average weather over various time periods ranging from a few weeks to decades to geological timescales. Whether and climate are ultimately determined by location, topography, and the exchange of radiant energy between the Sun, Earth, and space. Factors affecting the earth’s climate Incoming solar irradiance The earth system Surface Atmosphere (greenhouse gases, particles, etc) Clouds Solar irradiation: Solar constant Solar constant: The amount of solar energy received per unit of area outside the Earth’s atmosphere, normal to the direction of propagation of the light. Radiation Budget The Earths climate system constantly tries to maintain a balance between the energy from the Sun that is absorbed by the Earth, and the energy that goes from Earth back out to space. We refer to this process as Earths radiation budget. This radiation budget allows the Earth to maintain the moderate temperature range essential for life as we know it. The components of the Earth system that are important to the radiation budget are the planets surface, atmosphere, and clouds. Radiation Budget at the Top of the Atmosphere Albedo (a) The fraction of solar energy that is reflected back to space is called the albedo. Different parts of the Earth (surface and cloud cover) have different albedo. Over the whole Earth, about 30 percent of incoming solar energy is reflected back to space. What contributes to the global albedo? Clouds account for