Types of Climate.—The climate of the Panjab plains is determined by their distance from the sea and the existence of formidable mountain barriers to the north and west. The factor of elevation makes the climate of the Himalayan tracts very different from that of the plains. Still more striking is the contrast between the Indian Himalayan climate and the Central Asian Trans-Himalayan climate of Spiti, Lahul, and Ladakh.
Zones.—A broad division into six zones may be recognised :
- A 1. Trans-Himalayan.
- B 2. Himalayan.
- C. Plains 3. North Western.
- 4. Submontane.
- 5. Central and South Eastern.
- 6. South Western.
Trans-Himalayan Climate.—Spiti, Lahul, and Ladakh are outside the meteorological influences which affect the rest of the Indian Empire. The lofty ranges of the Himalaya interpose an almost insurmountable barrier between them and the clouds of the monsoon. The rain-fall is extraordinarily small, and, considering the elevation of the inhabited parts, 10,000 to 14,000 feet, the snowfall there is not heavy. The air is intensely dry and clear, and the daily and seasonal range of temperature is extreme. Leh, the capital of Ladakh (11,500 feet), has an average rainfall (including snow) of about 3 inches. The mean temperature is 43 Fahr., varying from 19 in January to 64 in July. But these figures give no idea of the rigours of the severe but healthy climate. The daily range is from 25 to 30 degrees, or double what we are accustomed to in England. Once 17 below zero was
Fig. 17. Average Barometric and Wind Chart for January.
recorded. In the rare dry clear atmosphere the power of the solar rays is extraordinary. "Rocks exposed to the sun may be too hot to lay the hand upon at the same time that it is freezing in the shade."
The Indian Zones — Meteorological factors.— The distribution of pressure in India, determined mainly by changes of temperature, and itself determining the direction of the winds and the character of the weather, is shown graphically in figures 17 and 18. The winter or north-east monsoon does not penetrate into the Panjab, where light westernly and northernly winds
Fig. 18. Average Barometric and Wind Chart for July.
prevail during the cold season. What rain is received is due to land storms originating beyond the western frontier. The branch of the summer or south-west monsoon which chiefly affects the Panjab is that which blows up the Bay of Bengal. The rain-clouds striking the Eastern Himalaya are deflected to the west and forced up the Gangetic plain by south-westernly winds. The lower ranges of the Pan jab Himalaya receive in this way very heavy downpours. The rain extends into the plains, but exhausts itself and dies away pretty rapidly to the south and west. The Bombay branch of the monsoon mostly spends itself on the Ghats and in the Deccan. But a part of it penetrates from time to time to the south-east Panjab, and, if it is sucked into the Bay current, the result is widespread rain.
Himalayan Zone.— The impressions which English people get of the climate of the Himalaya, or in Indian phrase "the Hills," are derived mainly from stations like Simla and Murree perched at a height of from 6500 to 7500 feet on the outer ranges. The data of meteorologists are mainly taken from the same localities. Places between 8000 and 10,000 feet in height and further from the plains enjoy a finer climate, being both cooler and drier in summer. But they are less accessible, and weakly persons would find the greater rarity of the air trying.
In the first fortnight of April the plains become disagreeably warm, and it is well to take European children to the Hills. The Panjab Government moves to Simla in the first fortnight of May. By that time Simla is pretty warm in the middle of the day, but the nights are pleasant. The mean temperature of the 24 hours in May and June is 65° or 66°, the mean maximum and minimum being 78 and 59. Thunderstorms with or without hail are not uncommon in April, May, and June. In a normal year the monsoon clouds drift up in the end of June, and the next three months are "the Rains." Usually it does not rain either all day or every day, but sometimes for weeks together Simla is smothered in a blanket of grey mist. Normally the rain comes in bursts with longer or shorter breaks between. About the third week of September the rains often cease quite suddenly, the end being usually proclaimed by a thunderstorm. Next morning one wakes to a new heaven and a new earth, a perfectly cloudless sky, and clean, crisp, cool air. This ideal weather lasts for the next three months. Even in December the days are made pleasant by bright sunshine, and the range of temperature is much less than in the plains. In the end of December or beginning of January the night thermometer often falls lower at Ambala and Rawalpindi than at Simla and Murree. After Christmas the weather becomes broken, and in January and February falls of snow occur. It is a disagreeable time, and English residents are glad to descend to the plains. In March also the weather is often unsettled. The really heavy falls of snow occur at levels much higher than Simla. These remarks apply mutatis mutandis to Dharmsala, Dalhousie, and Murree. Owing to its position right under a lofty mountain wall Dharmsala is a far wetter place than Simla. Murree gets its monsoon later, and the summer rainfall is a good deal lighter. In winter it has more snow, being nearer the source of origin of the storms. Himalayan valleys at an elevation of 5000 feet, such as the Vale of Kashmir, have a pleasant climate. The mean temperature of Srinagar (5255 feet) varies from 33 in January to 75 in July, when it is unpleasantly hot, and Europeans often move to Gulmarg. Kashmir has a heavy snowfall even in the Jhelam valley. Below 4000 feet, especially in confined river valleys the Himalayan climate is often disagreeably hot and stuffy.
Climate of the Plains.— The course of the seasons is the same in the plains. The jaded resident finds relief when the rains cease in the end of September. The days are still warm, but the skies are clear, the air dry, and the nights cool. November is rainless and in every way a pleasant month. The clouds begin to gather before Christmas, but rain often holds off till January. Pleasant though the early months of the cold weather are, they lay traps for the unwary. In October and November the daily range of temperature is very large, exceeding 30, and the fall at sunset very sudden. Care is needed to avoid a chill and the fever that follows. Clear and dry though the air is, the blue of the skies is pale owing to a light dust haze in the upper atmosphere. For the same reason the Himalayan snows except after rain are veiled from dwellers in the plains at a distance of 30 miles from the foot-hills. The air in these months before the winter rains is wonderfully still. In the three months after Christmas the Pan jab is the pathway of a series of small storms from the west, preceded by close weather and occurring usually at intervals of a few weeks. After a day or two of wet weather the sky clears, and the storm is followed by a great drop in the temperature. The traveller who shivers after a January rainstorm finds it hard to believe that the Panjab plain is a part of the hottest region of the Old World which stretches from the Sahara to Delhi. If he had to spend the period from May to July there he would have small doubts on the subject. The heat begins to be unpleasant in April, when hot westernly winds prevail. An occasional thunderstorm with hail relieves the strain for a little. The warmest period of the year is May and June. But the intense dry heat is healthier and to many less trying than the mugginess of the rainy season. The dust-storms which used to be common have become rarer and lighter with the spread of canal irrigation in the western Panjab. The rains ought to break at Delhi in the end of June and at Lahore ten days or a fortnight later. There is often a long break when the climate is particularly trying. The nights are terribly hot. The outer air is then less stifling than that of the house, and there is the chance of a little comparative coolness shortly before dawn. Many therefore prefer to sleep on the roof or in the verandah. September, when the rains slacken, is a muggy, unpleasant, and unhealthy month. But in the latter half of it cooler nights give promise of a better time.
Special features of Plain Zones.— The submontane zone has the most equable and the pleasantest climate in the plains. It has a rainfall of from 30 to 40 inches, five-sevenths or more of which belongs to the monsoon period (June — September) The north-western area has a longer and colder winter and spring. In the end of December and in January the keen dry cold is distinctly trying. The figures in Statement I, for Rawalpindi and Peshawar, are not very characteristic of the zone as a whole. The average of the rainfall figures, 13 inches for Peshawar and 32 for Rawalpindi, would give a truer result. The monsoon rains come later and are much less abundant than in the submontane zone. Their influence is very feeble in the western and south-western part of the area. On the other hand the winter rains are heavier than in any other part of the province. Delhi and Lahore represent the extreme conditions of the central and south-eastern plains. The latter is really on the edge of the dry south-western area. The eastern districts of the zone have a shorter and less severe cold weather than the western, an earlier and heavier monsoon, but scantier winter rains. The total rainfall varies from 16 to 30 inches. The south-western zone, with a rainfall of from 5 to 15 inches, is the driest part of India proper except northern Sindh and western Rajputana. Neither monsoon current affects it much. At Multan there are only about fifteen days in the whole year on which any rain falls.