Cirrus effects in the Halogen Occultation Experiment (HALOE) are investigated and methods are developed to use HALOE multiwavelength particulate extinction measurements for cloud identification. Techniques were explored to identify cloud layers from the extinction spectrum, vertical gradient, and magnitude. Results from HALOE measurements are presented, including cirrus climatologies and comparisons of cloud top height with independent measurements. ¿ 1999 American Geophysical Union