Light Speed Calculator

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Did you know the velocity of light changes depending on the humidity, temperature, and pressure of the surrounding air? While the speed of light is sometimes thought to always be exactly 299,792,458 meters per second, that is actually the speed of light in a vacuum; the speed can change a significant amount due to interactions with particles in the atmosphere. This website uses Elden's Equation to find the approximate speed of light in any given environment, provided the temperature (Celsius), humidity (humidity percentage), and barometric pressure (mm Hg).

Enter Temperature (Celsius):
Enter Humidity (%):
Enter Barometric Pressure (mm Hg):

Light Speed (m/s):