Driver's vision enhancer and DRS Technologies. All objects above Absolute zero (−273.15 °C / −459.67 °F) emit infrared radiation (IR), an invisible form of light beyond the optical spectrum. The optical spectrum is part of the electromagnetic energy spectrum which consists of ultraviolet, visible, and near, middle, and far-infrared energy. Only a small part of the optical spectrum is visible to the unaided eye. The Sun emits energy across the entire electromagnetic spectrum. Solar energy strikes the surface of objects. Some of that energy is absorbed and stored as heat (thermal energy). After sunset, this thermal energy remains and is emitted in the
Ultraviolet communication in butterflies communicate their receptivity to males using their ultraviolet communication system. The ultraviolet reflection is thought to be concentrated to the ventral side of a female’s hind wing. Yoshiaki Obara determined this experimentally by comparing the number of approaches to different parts of butterfly wings. The results showed that the female’s ventral hind wing was the greatest releaser of male sexual behavior. Although ultraviolet reflectance releases the sexual behavior, the strongest reflection of UV light is not the strongest releaser for the behavior. As a result, male white cabbage butterflies must have a preference for a certain level of UV reflectance