is frequently used to characterize the conditions that give rise to mirages, such as in this example: "Abnormal refraction
responsible for mirages
is invariably associated with abnormal temperature distributions that yield abnormal spatial variations in the refractive index
." Yet mirages and the conditions that give rise to them are very common. It would appear that, when these terms are used, normality is something defined by the free atmosphere
, far from surfaces. Certainly, by that measure, the refractive index gradients near a surface are abnormal. It is misleading to imply that either the refractive structures or the mirages are abnormal or anomalous when they are so common near the earth's surface, merely because they are not as common farther away from that surface.
Copyright 2022 American Meteorological Society (AMS). For permission to reuse any portion of this work, please contact email@example.com. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act (17 U.S. Code § 107) or that satisfies the conditions specified in Section 108 of the U.S.Copyright Act (17 USC § 108) does not require AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, require written permission or a license from AMS. Additional details are provided in the AMS Copyright Policy statement.