The Sun's lower chromosphere is observable from Earth by using a narrow band
Calcium filter. It's deep blue/UV spectrum however renders little of the upper Chromosphere.

Higher layers of the chromosphere are typically revealed by a narrow band of red light
via a Hydrogen-alpha filter, which conversly shows little activity close to the surface.

Using a novel processing technique, both lower (blue) and upper (red)
Chromospheric data sets were combined to reveal both layers in a single image.

AP130 + Coronado 90 H-alpha data
AP110 + MLAstro700 Spectroheilograph (tuned to Ca-H spectral line) Calcium data

Copyright Peter J Ward 2026