On the Height of Formation of H-Alpha in the Solar Chromosphere

Several features of Ha limb spectra, including the line emission beyond the continuum limb, are analyzed to yield information about the height of formation of Ha in the solar chromosphere. It is concluded that de Jager's suggested value for the height of unit optical depth at the line center (5000 km) is too high. For the chromospheric features in these spectra the height of formation lies in a range from 1500 km (above a sunspot) to 2700 km. This is consistent with the limb profile analysis which yields a range from 1600 to 3000 km for a hypothetical mean chromosphere.