_Squall._--1. A sudden storm of brief duration; closely akin to a thunderstorm but not necessarily attended by thunder and lightning. 2. A sudden brief blast of wind, of longer duration than a gust. _Squaw Winter._--In North America, a brief cold spell popularly reputed to precede Indian summer. _Static._--(See _stray_.) _Storm Card._--A device intended for use on shipboard in determining the direction of a storm center from the ship. _Storm Water._--The water resulting from a heavy and rapid fall of rain; especially the portion that occurs as run-off. (The term has been used mainly in connection with the subject of sewers.) _Strato-cumulus._--A form of cloud. (See Chapter VI.) _Stratosphere._--The upper region of the atmosphere, formerly called the _isothermal layer_, in which there is no marked or systematic decrease of temperature with altitude. The stratosphere is free from clouds (except occasional dust clouds) and from strong vertical air currents, and its circulation appears to be more or less independent of that of the lower atmosphere. The height of its base, which varies with latitude and otherwise, averages between 6 and 7 miles. (Cf. _troposphere_.) _Stray._--A natural electromagnetic wave in the ether. The term is used in reference to the effects of such waves in producing erratic signals in radiotelegraphic receivers. Strays are known collectively as _static_. _Summer Day._--A day in which the temperature reaches or exceeds 77 degrees F. _Sun Dog._--A mock sun or parhelion. “_Sun Drawing Water._”--The sun popularly said to be “drawing water” when crepuscular rays extend down from it toward the horizon. _Sunshine Recorder._--An instrument for recording the duration of sunshine; certain types also record the intensity of sunshine. _Synchronous Chart._--A form of synoptic chart, such as the ordinary weather map, which shows the meteorological conditions prevailing over any area at a given moment of time. _Synoptic Chart._--A chart showing the distribution of meteorological conditions over an area at a given moment or the average conditions during a given period of time, such as a month or a year. _Table-cloth._--A sheet of cloud that sometimes spreads over the flat top of Table Mountain, near Cape Town. _Tangent Arc._--Any halo that occurs as an arc tangent to one of the heliocentric halos. _Term Hours._--Prescribed hours for taking meteorological observations. _Thermal Belt._--A well-defined zone, found on some mountain-sides, in which vegetation is particularly exempt from frosts in spring and autumn. Also called _verdant zone_. _Thermograph._--A self-registering thermometer.