Radiatively important atmospheric constituents

This chapter discusses the chemical constituents and radiative properties that characterize our atmosphere and drive our climate system. Earth’s climate system is always at work; it receives, absorbs, and reflects radiative energy from the sun in higher quantities at the tropics and redistributes the heat from low to high latitudes to compensate for the lack of heat received at the poles. This transport and exchange of heat determines the global atmospheric circulation patterns and, thus, the distribution of temperature and precipitation across the globe. However, this mechanism alone cannot provide the earth with the adequate amount of heat to enable and sustain life in this planet. Instead, radiatively important gases in the earth’s atmosphere, referred to as greenhouse gases, play a key role in keeping a balance between incoming short wave and outgoing long wave radiation by acting like an insulating blanket regulating the temperature of our planet. These gases, mainly water vapor (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ozone (O3), all act as effective insulators; their concentrations in our atmosphere significantly affect the overall temperature of our atmosphere. Without the greenhouse gases, our atmosphere would be unpleasantly cold and likely uninhabitable. Human-driven activities have enhanced the greenhouse effect by changing the concentrations of these mentioned gases along with introducing other chemicals like sulfates, chlorines, other halogens, and other gases and particles that chemically and physically interact in the earth’s atmosphere. It is then of utmost importance to understand the structure of atmospheric gases and particles, their chemical and physical interactions, their lifetimes, and how human activities can and are altering this naturally occurring effect.