H [Greek symbol alpha]—hydrogen-alpha; either abbreviate both words or spell both out. Do the same for hydrogen-beta and hydrogen-gamma.
hailfall—one word, by analogy with rainfall
headings—Create a style sheet for each unique print document. For online content, sentence style has been preferred by UCAR Communications since 2010. A heading that includes a colon takes an initial cap after the colon. Example: Zooming in: Winter beauty. [02/2012]