_Glaze._--Term applied by the U. S. Weather Bureau to a smooth coating of ice on terrestrial objects due to the freezing of rain; often popularly called “sleet.” In Great Britain such a deposit is called _glazed frost_. A deposit of glaze on an extensive scale constitutes an “ice storm.” _Glory._--A series of concentric colored rings seen around the shadow of the observer, or of his head only, cast upon a cloud or fog bank. It is due to the diffraction of reflected light. _Gouffre._--(See _brontide_.) _Gradient._--Change of value of a meteorological element per unit of distance. The gradients commonly discussed in meteorology are the horizontal gradient of barometric pressure, the vertical gradient of temperature, and the vertical gradient of electric potential. British meteorologists now prefer the term _lapse-rate_ to _vertical gradient_. _Graupel._--A kind of granular snow, sometimes called _soft hail_. _Green Flash._--A bright green coloration of the upper edge of the sun’s disk, sometimes seen when the rest of the disk is below the horizon, at sunrise or sunset. _Growing Season._--In agricultural meteorology, the interval between the last killing frost in spring and the first killing frost in autumn. _Gust._--A sudden brief increase in the force of the wind. Most winds near the earth’s surface are made up of alternate gusts and _lulls_, the majority of which are too brief to be registered by an ordinary anemometer. _Hail._--Balls or irregular lumps of ice, often of considerable size, having a complex structure; large hailstones generally have a snowlike center, surrounded by layers of ice, which may be alternately clear and cloudy. Hail falls al-most exclusively in connection with thunderstorms. For so-called “soft hail” see _graupel_. (Cf. _sleet_.) _Hail Rod._--A device analogous to a lightning rod, supposed to have the property of averting the fall of hail. Hail rods have been especially popular in France, where they are called _paragrêles_. Large hail rods of recent construction are known as “electric Niagaras.” _Hail-shooting._--Bombarding the clouds to prevent the fall of hail. _Halo._--A generic name for a large group of optical phenomena caused by ice crystals in the atmosphere. The commonest of these phenomena is the _halo of 22 degrees_ (i. e., of 22 degrees radius) surrounding the sun or moon. The _halo of 46 degrees_ and the rare _halo of 90 degrees_, or _halo of Hevelius_, also surround the luminary. Other forms of halo are the _tangent arcs_, _parhelia_ (_or paraselenæ_), _parhelic_ (or _paraselenic_) _circle_, _anthelion_, etc. _Harmattan._--A dry, dusty wind of the west coast of Africa, blowing from the deserts.