54 The Ottawa Naturalist. [June 



summer is simply a dry fog where the impurities in the atmos- 

 phere remain a long time owing to the absence of rain. The 

 greater part of the impurities are from forest fires. 



Of atmospheric optics a few words may be said. Of these 

 the most familiar phenomenon is the rainbow. It is simply a 

 color sensation due to the double refraction and reflection of the 

 sun's rays by globules of water situate in the surface of a cone 

 of which the eye is the apex. The higher the sun the lower the 

 bow, and the greatest bow possible is a semi-circle, when the 

 sun is just rising or setting. Theoretically no two observers see the 

 same rainbow, for the bow has no real or material existence. 



Rings around the sun and moon are divided into two 

 classes — the corona of small diameter and the halo of greater 

 diameter. The corona is a diffraction phenomenon, while the 

 halo is due to reflection and refraction of the light by the ice 

 crystals or ice needles in the higher regions of the cirrus clouds. 

 There is a great variety in the distribution of halos — sometimes 

 the rings are wholly separate and sometimes they intersect. 

 The points of intersection are usually more or less light patches, 

 ;and are called mock suns, or sun dogs or parhelia ; for the moon, 

 paraselenae. 



When one layer of air lies in contact with another of differ- 

 ent temperature and density, the bounding surface between the 

 two, if sharply defined will reflect light perfectly and hence 

 images of objects become visible. This phenomenon is called 

 mirage, and I have frequently seen it in the Alaskan archipelago 

 and less frequently on the plains of our North-west. 



There is no problem in the wide range of science in the 

 public eye that admits of so ready solution as weather. Is is the 

 pseudo-scientist, the charlatan — who surrounds himself with a 

 halo of scientific terms, favorite ones being opposition and con- 

 junction of planets — writes of astronomical computations, et 

 cetera, that misleads the public through his bold and at times 



