A liquid laser that is robust in air and tunable by wind
Laser & Light sources
Self-leveling Laser Level - Huepar Box-1G 150ft/45m Outdoor Green Cross Line Laser Level with Vertical Beam Spread Covers of 150°, Selectable Laser Lines, 360° Magnetic Base and Battery Included - - Amazon.com
How Does Temperature Affect the Wavelengths of Lasers?