During thunderstorms the record from an electrograph shows large sudden excursions, the trace usually going off the sheet with every flash of.
The number of thunderstorm days is probably a less exact measure of the relative intensity of thunderstorms than statistics as to the number of persons killed annually by lightning per million of the population.
The frequency and intensity of thunderstorms are unquestionably greater in the Rocky Mountain than in the New England states, but the difference is not so great as the statistics at first sight suggest.
Even at the same place thunderstorms vary greatly in intensity and duration.
[[Table Xii]].-Diurnal Variation of Thunderstorms. centages.
MacDowall (86) and others have advanced evidence in favour of the view that thunderstorms are most frequent near new moon and fewest near full moon.
St Elmo's Fire.-Luminous discharges from masts, lightning conductors, and other pointed objects are not very infrequent, especially during thunderstorms. On the Sonnblick, where the phenomenon is common, Elster and Geitel (87) have found St Elmo's fire to answer to a discharge sometimes of positive sometimes of negative electricity.
The sixth book is devoted to the explanation, in accordance with natural causes, of some of the more abnormal phenomena, such as thunderstorms, volcanoes, earthquakes, &c., which are special causes of supernatural terrors.
These are the conditions of Buganda, a country with an annual rainfall of from 60 to 80 in., a regular West African climate, and severe and frequent thunderstorms. Much the same may be said about the Western province, except for the cooling influence of the Ruwenzori snow range, which pleasantly affects Toro and northern Ankole.
The climate is characterized by extreme heat in the summer and cold in the winter; among the mountains the snowfall is heavy, and thunderstorms are frequent, but there is comparatively little rain.
And S.W., bringing warmer weather with rain and snow in winter, and causing days of great heat and humidity, with thunderstorms, in summer.
Salamanders, far from being able to withstand the action of fire, as was believed by the ancients, are only found in damp places, and emerge in misty weather only or after thunderstorms, when they may appear in enormous numbers in localities where at other times their presence would not be suspected.
Although of reduced strength in the summer, they still suffice to dominate weather changes; it is during the approach of a low pressure centre that hot southerly winds prevail; they sometimes reach so high a temperature as to wither and blight the grain crops; and it is almost exclusively in connection with the cloudy areas near and south-east of these cyclonic centres that violent thunderstorms, with their occasional destructive whirling tornadoes, are formed.
Thunderstorms occur throughout the year, but are most common in the summer.
The mountain chain immediately overhanging it, the high temperature of the sea washing it,,the frequent thunderstorms to which it is subject, the moist atmosphere of its equatorial situation, and the shorter regime of the dry south-east wind are the principal causes of the heavier rainfall on the west coast.
Thunderstorms are frequent and occasionally very severe, between May and September; the annual average of thunderstorms for the decennium1888-1897was 505, the greatest frequency was in May (average 100.3) and in June (average 90.7); the severity of these storms may be imagined from the fact that in a half-hour between 5 and 6 p.m.
Thunderstorms are frequent in the summer.
His sphere of influence was the nocturnal heavens, thunderstorms at night being attributed to him, those by day to Jupiter.
There is a so-called wet season, which begins early in July and lasts for a month or six weeks, the rain coming in the form of short afternoon thunderstorms. About a third of the precipitation occurs during July and August, but after August the monthly precipitation is steadily less until March, in which month only about 3% of the annual rainfall occurs.
The surrounding country for many miles is absolute desert, except after rare but terrible thunderstorms, when the dry bed of the Little Fish river is suddenly filled with a turbulent stream, the water finding its way into the bay.
Portugal is very rarely visited by thunderstorms; but shocks of earthquake are frequently felt, and recall the great earthquake of Lisbon (q.v.) in 1755.
Local thunderstorms and cloud-bursts are a characteristic phenomenon, inundating limited areas and transforming dried-up streams into muddy torrents carrying boulders and debris.
The chief paths of depressions are from southwest to north-east across England; one track runs across the south-east and eastern counties, and is that followed by a large proportion of the summer and autumn storms, thereby perhaps helping to explain the peculiar liability of the east of England to damage from hail accompanying thunderstorms. A second track crosses central England, entering by the Severn estuary and leaving by the Humber or the Wash; while a third crosses the north of England from the neighbourhood of Morecambe Bay to the Tyne.
The wettest month for most parts of England is October, the most noticeable exception being in East Anglia, where, on account of the frequency of summer thunderstorms, July is the month in which most rain falls, although October is not far behind.
The hot westerly winds of summer make the air oppressive, though violent thunderstorms, in which form the northern districts receive most of their scanty rainfall, occasionally clear the atmosphere.
Thunderstorms release tremendous amounts of energy.