Increasing levels of greenhouse gases, resulting from industry and the burning of fossil fuels, may result in rising global temperatures, causing coastal flooding and major climatic changes. Incoming solar radiation penetrates the atmosphere, but much of this radiation is held within the earth's atmosphere by gases such as carbon dioxide, methane, and ozone. This process maintains the earth's temperature in a range that is hospitable to life. The wavelengths of infrared radiation are shorter than radio wavelengths and longer than light wavelengths. By detecting infrared radiation, astronomers can observe stars and nebulas that are invisible in ordinary light but that emit infrared radiation.
Infrared photography is a diagnostic tool in medicine and is useful in agriculture and industry.
Infrared techniques reveal conditions in the body that are not visible to the eye or recorded by X rays. Remote sensing uses aerial and orbital infrared photography to monitor crop conditions in large agricultural areas and to locate mineral deposits. In industry, infrared photography is used to monitor the quality of products. Conservation includes the control of resources for economic purposes and the maintenance of national parks, wilderness areas, historic sites, and wildlife. Natural resources are classified as renewable or nonrenewable.