Abstract: Several embodiments of an apparatuses and method for sensing objects in a volume of interest are provided, including optionally sensing weather phenomena such as snow, ice, fog and the like by illuminating the volume with a laser pulse which is highly absorbed by the phenomenon and another laser pulse which is highly reflected, and sensing phenomenon presence by the returned pulses. Another aspect involves LIDAR utilizing a plurality of wavelengths. Further aspect include apparatus combining LIDAR and thermal imaging utilizing a single photodetector biased at different polarities to switch between the LIDAR and thermal imaging modes, providing a 3D thermal map of the volume of interest. All features may be combined in a single embodiment of the invention, or various aspects may be combined at will. A dual polarity photodetector for use in such combined LIDAR and thermal imager is also provided. Methods of using various embodiments are also provided.