Thermal Weapon Sight

A Thermographic weapon sight or Thermal Weapon Sight is a device combining a compact thermographic camera

Thermographic camera

A thermographic camera or infrared camera is a device that forms an image using infrared radiation, similar to a common camera that forms an image using visible light...

and an aiming reticle. They can be mounted on a variety of small arms as well as some heavier weapons.

As with regular thermal sensors, thermal weapon sights can operate in total darkness or through light concealment (smoke, haze, fog, light rain). The thermal scope can be quite useful in places with snow as the large contrast in temperatures between the snow (inherently cold) and any heat source (such as humans) making it very easy to distinguish between the two.