Abstract: An illumination apparatus for indicating the liquid level in a chemical storage tank is provided. The apparatus includes a transparent globe surrounding a light bulb mounted by flanges to upper portions of a storage tank, and being illuminated by an external electrical supply. Optionally the light bulb may be cooled by either allowing gas or air contained in the storage tank pass through a hole in the globe to interact with and cool the light bulb, or supplying a gas to the globe and circulating it around the light bulb. A shadow line is cast at the surface level of the liquid in the tank, and can be visibly seen through the translucent walls of the tank from some distance away.