Blue Haze Research Articles

Some remarks on the nature and origin of noctilucent cloud particles

Continuous spectra of the light from noctilucent clouds, recently obtained by N.I. Grishin near Moscow, U.S.S.R., are analysed after accounting for the selective attenuation of the lower atmosphere and the spectrum of sunlight. It is found that the spectra may be explained in terms of primary scattering of direct sunlight by dielectric spheres with a maximum radius of 0·.4 μ, and certain night sky emissions. The apparent absence of any nocturnal ozone layers above 35 km is also noted. The possibility of an ice composition of the clouds formed by condensation of terrestrial water vapor is examined and found unjustified on physical grounds. Rather a silicaceous or similar composition and an interplanetary origin for the cloud particles is favoured and a close relation with the Martian “blue haze” is suggested.

Note: the Blue Haze of Mars.

Note: the Blue Haze of Mars.

Blue Haze and the Vertical Structure of the Martian Atmosphere.

The atmospheric haze which usually obscures the surface of Mars in blue light is probably a condensate rather than a dust because it can clear away rapidly. Carbon dioxide and water vapor are both present in the atmosphere, and condensation of each into the solid phase has been suggested to explain the blue haze. Calculations are carried out by assuming a convective atmosphere with a surface temperature of +10 C for the subsolar point and a lapse rate of 3.7 C/km. When the optical properties of clouds produced in such an atmosphere are determined with the aid of the Mie theory of scattering, it is found that (1) carbon dioxide ice clouds are far too opaque to be the cause of the blue haze; (2) water ice clouds can cause the blue haze if the surface frost point lies near -90 C. The second result is consistent with the failure of all modern attempts to detect water vapor spectroscopically in the Martian atmosphere, since the total precipitable water content corresponding to such a frost point is only 2 These results indicate that the author's earlier suggestion of carbon dioxide ice clouds should be rejected.

Fluorescence in planetary atmospheres

It is pointed out that ions and free radicals will exist in the high atmospheres of the planets and that these ions will absorb and fluoresce in the visible and near ultra-violet radiations. Applications of this effect to the problem of the colour of Venus, the blue haze of Mars, the variation of brightness of Jupiter and the haze of Mercury are discussed. The presence of a tenuous atmosphere on Mercury is justified by its equilibrium with the local interplanetary gas.

THE BLUE ARCS OF THE RETINA

As early as 1825, Purkinje¹called attention to a phenomenon that has become more intriguing as more facts have been added concerning it. If an observer in a dark room, preferably with one eye closed, looks a little to the temporal side of a circle or band of light, he will see, in addition to the source of light (the primary stimulus), two curved bands of bright blue beginning at the stimulating light and arching across the visual field to the region of the blind spot. At times the enclosed elliptical area is also filled with a faint blue haze. Several subsequent workers (Zeeman,²Tscherning³and Hubbard⁴) independently reported the same discovery, being incognizant of Purkinje's original paper because of its inaccessibility. The cause of the phenomenon has been explained in varying ways. While Purkinje recognized a relationship to the anatomic structure of the retina, he

VI. On the sensitive state of electrical discharges through rarefied gases

It has frequently been remarked that the luminous column produced by electric discharges in vacuum-tubes occasionally displays great sensitiveness on the approach of a finger or other conductor to the tube. The exact effect of such approach varies considerably with the circumstances of the discharge. In many instances the luminous column is repelled; in others, and especially when the finger is brought into actual contact with the glass, the column is severed; and in the latter case, in addition to the luminosity previously present, there often appears proceeding from the interior of the tube, at the point where the finger rests, the blue haze which usually characterises the negative end of a discharge. In some cases the discharge is so powerfully affected that the well-known green or blue fluorescence appears on the side of the tube opposite to the point touched. The degree of sensitiveness varies between wide limits. Discharges frequently occur in which close observation is necessary to detect any trace of it, while others may be produced so sensitive that the magnetic action of a powerful electro-magnet is hardly more marked than the action which is due to it as a conductor. The condition in question does not appear to be confined to any particular gaseous medium or to any special form of tube; and it is in fact probable that in almost any tube sensitiveness may be produced by adopting suitable precautions. This state of sensitiveness may be exhibited by stratified discharges, but it is more commonly associated with those which show no clear traces of stratification. It is not however universally present in either kind of discharge.