Urban climates are climates modified by the presence of urbanized areas. Urban climates include modifications to all the main elements that comprise our weather and climate: temperature, radiation, wind flow, humidity, atmospheric composition, clouds, and precipitation. These changes come about because urbanization creates significant modifications to the land surface and these modifications affect how energy and mass are exchanged between the surface and the atmosphere. Urban climates now affect nearly half of the world's population. Most residents of developed nations live in cities while less-developed nations have experienced recent rapid rates of urbanization and the emergence of megacities. Urban climates represent an unintentional or inadvertent change to climates. Urban climates are superposed on both the background climate of a location as well as any regional climate effects due to the landscape such as a coastal or valley location of a city. Modified urban climates influence the energy and water use ...