(*For this section an article on "The Climate of Poona" by Dr. S.K. Pramanik, M.sc., Ph.D., D.I.C., Indian Meteorological Department, has been largely drawn upon.)

POSSESSED of a high altitude, a soil free from alluvial deposits and prevalence of westerly breezes, Poona has a climate dry and invigorating.

Seasons.

The year may be divided into three seasons, the cold season from November to February, the hot season from March to May, and the wet season from June to October. In the cold season dry easterly land winds prevail during most part of the day and coll westerly valley winds in the night, and from February onwards, there is sea-breeze in the evening. By about the middle of March, the temperature rises somewhat rapidly and hot breeze of variable direction prevails during day time. The hot season may be said to begin in the middle of March and end by June, though the hot winds and other characteristics of the hot weather are mostly over by the middle of May. In April and May the maximum temperature at Poona and several other places in the district often rises above 100’F and temperature as high as 108-110’F have been recorded.

Seasons.

At the beginning of the hot weather the wind blows from the east in the morning and from the west in the afternoon. The sea breeze that sets in towards evening on most days in the months of February to May brings considerable relief on hot days during evening and the early part of the night. Thunderstorms occasionally alleviate the heat but the precipitation sometimes renders the air sultry.

During the hot season there is haze. April and May, though the hottest, are not the driest months. In the east and centre of the district, sometimes early in May, but as a rule not till towards the close of the month, after three or four oppressive days, in the afternoon clouds gather in the east in great masses, and with a strong blast from the north-east, drive west with thunder and heavy rain. The thunderstorms are occasionally accompanied by violent winds, and sharp showers, and also hail on rare occasions.

Rainfall.

Over the whole district the chief supply of rain is from the south-west monsoon which begins about the middle of June and lasts till the end of October. The returns show marked variations from year to year at the different rain stations.

Rainfall statistics are available for 16 stations in different parts of the district. The following table gives these statistics:—

RAINFALL IN POONA DISTRICT

Lonavle is situated at the crest of the Sahyadris at the head of the Bor pass, at a distance of about 40 miles west of Poona. As compared to all the other stations in the district, the rainfall at Lonavle, viz., 181" (mean for 52 years), is several times more. Its location is responsible to divide the district into three regions, the western, central and eastern.

The Western region, represented by Paud, Vadgaon (Mawal) and Talegaon-Dabhade and lying between Poona and Lonavle, is situated in the lee of the Sahyadris and consists of its slopes and a few miles beyond to the east. This region falls west of longitude 73' 45’E. It has a certain and fairly sufficient rainfall. The mean is 63.91" for Paud, 40 Vadgaon (Mawal) and 38.25" for Talegaon-Dabhade. During a period of 62 years, Paud had more than 40 inches for 59 years and Vadgaon recorded more than 40" for 30 years and more than 30" for 48 years.

The central region lies between longitudes 73' 45' and 74’E. This region may be further sub-divided into two, viz., the northern, above latitude 19’N., represented by Junnar and Ghod, and the southern represented by Khed, Alandi, Poona and Saswad. The northern sub-region shows a higher mean than the southern one. The mean for Junnar is 53.4" and for Ghod 51.4". The mean for Khed is 25".; for Alandi 22.56" ; for Poona 26.63" ; and for Saswad 24.98". Over a period of 62 years, more than 20" was recorded at Junnar for 54 years and at Ghod for 55 years. Over the same period, Khed and Saswad recorded more than 20" for 53 years and 34 years respectively. Over a period of 52 years, Poona and Alandi recorded more than 20" for 40 years and 36 years respectively. It will be noticed that though the rainfall is less in the central region than in the western region still it is steady.

The part of the district east of longitude 74’E forms the eastern region. This region consists mostly of undulating plains. The range of hills that start from the Sahyadris and go west-east almost slope into these plains. This region is reputed to be a region of uncertain rainfall. But this region may be divided into two sub-regions, one of which is the area round about Daund, Baramati and Indapur. Daund is situated on the Bhima and is 48 miles to the east of Poona. Baramati is situated on the Karha and is 50 miles south-east of Poona. Indapur is 80 miles south-east of Poona. These three stations from the south-east portion of the district and are between the Bhima and the Nira rivers. The southern part of the triangle comes under the Nira Canal systems. The records for these stations show more rainfall as compared to the other stations in the eastern zone. Daund, Baramati and Indapur have more or less the same mean rainfall, viz., 25". Over a period of 49 years, Daund recorded more than 20" for 19 years and more than 15" for 33 years. Over a period of 62 years Baramati and Indapur recorded more than 20" for 28 years and 35 years respectively, and more than 15" for 50 years and 52 years respectively. Sirur, Talegoan-Dhamdhere, and Jejuri represent the other sub-region of the eastern region. They have a mean rainfall round about 20". Over a period of 62 years, Sirur, Talegaon-Dhamdhere, and Jejuri recorded more than 20" for 24, 31 and 19 years respectively, and more than 15" for 39, 45 and 34 years respectively. The area represented by these three stations has the lowest and most uncertain rainfall in the district.

Temperature.

In contrast to the maritime climate experienced by stations like Bombay on the west coast, Poona enjoys & continental climate characterised by large diurnal ranges of temperature. The following table is based on observations from 1881 to 1940 and gives the means of daily maximum and minimum for each month for poona. The table also gives the highest temperature recorded and the lowest recorded in each month.

The mean temperature is lowest in December. It rises steadily thereafter until the maximum is reached in May. With the onset of the monsoon in June, day temperature suddenly fall and by August the mean maximum temperature reaches its lowest value in the year. From September the temperature begins to rise again until the advent of the cold season in November. The daily range of temperature is least during the months of July and August, while during the cold season it is usually large, the maximum range being in February. During these 60 years the maximum temperature recorded was 110’F on 30th April 1987 and 7th May 1889. The minimum recorded during 1881-1940 was 35’F on 17th January 1935.

Humidity.

The following table gives for Poona the means of dry bulb and wet bulb temperatures, the relative humidity and the vapour pressure for each month. The table is based on figures available at the Meteorological Office, Poona.

Average for 8 a.m are based on data for the years 1891-1940 and those for 5 p.m. on data for the years 1936-40.

MEANS OF DRY AND WET BULB TEMPERATURES.

Situated as it is on the lee side of the ghats, Poona is much drier than places on the coast line. Even in the monsoon months of June, July, August and September, the mean monthly relative humidity never exceeds 84 per cent, The diurnal variation of temperature or humidity is least in the monsoon months. The relative humidity is high in the morning but is considerably reduced in the evening in winter and summer months. March and April are the driest months. On a few days in the month of May and sometimes also early in June, before the onset of the monsoon, nights in Poona become rather uncomfortable on account of the high temperature combined with a fairly high percentage of humidity.

Barometric Pressure.

The following table gives the mean pressure at Poona. Averages for 8 a.m. are based on data for the years 1891-1940 and those for 5 p.m. for the years 1936-1940.

MEAN PRESSURE AT POONA

These observation show that from October to March the barometric pressure is over the annual mean and from April to September the pressure is below the annual mean. The month of least pressure is June. Then come July, August, September, i.e., the monsoon months, and May. December pressure is the highest in the year.

Cloudiness.

The mean cloudiness estimated in tenths of sky covered is given in the following table. The average cloudiness in Poona, taking into account all kinds of clouds, low, medium and high, is less than five-tenths (or half of the sky) in all the months except during the monsoon period. On a large number of days during the winter months and also during the early summer, we have blue skies and brilliant sunshine.

MEAN CLOUDINESS IN POONA.

Winds.

A remarkable feature of Poona winds is their rareness from the south. The direction of the prevailing wind is NW to W in January and February. With the commencement of the hot weather, the direction slowly changes to the west and continues westerly right up to the end of the monsoon in September. October is a month of variable winds, While easterly winds predominate in November and December. During May and the rainy season the direction of the wind throughout the 24 hours is from the west. From the month of October to February calm prevails in the morning approximately between 8 a.m. and 10 a.m. Before the period of calm the direction of the wind is W. After the calm the easterly wind begins and continues till 7 p.m. in october, November and December. After seven in the ecening the direction changes and the westerly breeze starts. In January, February, March and April the period of easterly winds lasts only for a few hours from 10 a.m. onwards.

Though the poona district is situated to the east of the ghats, towards evening there is a sudden flow of air-the evening sea breeze-from WNW direction on most days of the months of February, March and April and part of May, characterised by its greater gustiness, humidity and lower temperature.

The following table gives the number of days with wind force (in miles per hour) and the mean wind speed:-

NUMBER OF DAYS WITH WIND FORCE AND MEAN WIND SPEED IN POONA

The following table gives the percentage number of days for various directions of wind in Poona :

DIRECTION OF WIND IN POONA

Thunderstorms Squalls, etc.

The following table gives the frequencies of thunderstorms, hail, squalls and fog at Poona in each month of the year based on observation from 1935 to 1944.

FREQUENCIES OF WEATHER PHENOMENA AT POONA.

Thunderstorms occur generally during the hot months of April and May, before the onset of the monsoon in June, and in September and October associated with the withdrawal of the monsoon. Some of the thunderstorms in April and May are accompanied by squally winds, heavy rain and hail. Morning fog occurs, though very infrequently, in Poona during the month of October and in the winter season from November to January.

Dew and Fog.

Dews appear in the latter part of October and last till the end of February. The difference between the percentages of relative humidity in the morning and in the evening goes on in creasing from October. The wind speed during these months is not more than 4.2 miles per hour. The range of temperature between the daily maximum and daily minimum is fairly high. All these contribute to the formation of dew.

Fogs are rare in the eastern plains. They occur in the early mornings in September, October, November, December and January but disappear by half-past nine. They are generally visible in the valleys on the banks of rivers. In the western hills mists are common from May to September. Sometimes mists rise from the Konkan and fly east with great swiftness. At other times when the air is still, the mist stretches over the Konkan like a sea of milk, the tops of hills standing out like islands. After the monsoon sets in early in June, except during occasional breaks, the western hills are shrouded in drenching mists and rain clouds.

The acreage under different crops in the various talukas of the district in 1942-43 brings out the peculiarities of the sub-regions very clearly.

THE ACREA UNDER DIFFERENT CROPS IN THE VARIOUS TALUKAS OF POONA DISTRICT (1942-43).

In the case of cereals, the western talukas of Mawal and Mulshi show a predominance of rice. In the central tract, Junnar, Ambegaon, Khed, Haveli and Purandar show a predominance of bajri, while the eastern talukas Sirur, Daund, Bhimthadi and Indapur show a predominance of javari. In the central belt rice though not predominant is important. The western portions of these talukas are rice zones.

In the case of pulses, the central zone shows predominance, the eastern zone comes next and the western zone comes last.

In oil-seeds, the eastern zone leads particularly in the productionof safflower; then comes the central zone; and the western zone comes last.

In the case of sugarcane, the Bhimthadi and Indapur Talukas alone are prominent. This being the canal zone this is natural. The Mutha Canals in Haveli also show a concentration of sugarcane there.

In the case of potatoes and other vegetables, the central zone leads the other two zones. The north central zone shows marked predominance in potatoes while the southern zone appears more favourable for green vegetables, mosambi and other fruits.