A thermal column (or thermal) is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and an example of convection. The Sun warms the ground, which in turn warms the air directly above it.. Dark earth, urban areas and roadways are good sources of thermals.
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Infrared (IR) radiation is electromagnetic radiation with a wavelength between 700 nm and 300 µm, which equates to a frequency range between 1 THz and 430 THz—a span of more than three orders of magnitude.
Infrared vs Microwave, 
