Thermal emissions from the lava cause an increase in the frequency of light surrounding the flow. Light maintains the same wave-speed, regardless of frequency. Therefore, we know that the wavelength is indirectly proportional to the frequency, and that is the frequency is increased, the wavelength decreases.

For a certain temperature, the frequency and wavelength will be modified to corresponding values. We know that the visible spectrum can be broken down into colors, each with unique wavelengths. The wavelength of red is from 622-780 nanometers.Therefore, the lava glows red when the temperature is increased to where the frequency is between 482 and 384 THz. As the frequency is increased, the wavelength would decrease. So, theoretically, ***really*** hot lava would look orange, yellow, green, blue and violet!! The lava is termed a 'black body radiator.' Ask your teacher what that is.