The Climate Of The Continental Regions
By Waqar Awan
The continental regions of the world share some common phenomena, viz., summer rain maxima, large seasonal variations in temperatures, very low relative humidity and large difference in the day and night temperatures.
The continental regions-far removed as they are from any water body like seas and oceans- exhibit extreme in their nature of climate. In summers these areas are warm to very hot depending on the latitude they lie. For instance at Moscow, despite its well-known subzero temperatures, the mid-day thermometer often exceeds 90 F in summers. In central Asia, at Tashkent, about 10 degrees lower in latitude, temperature as high as 106 F are commonly observed. While at Lahore, a further 10 degree lower location, situated at 31 degrees North, temperatures of the order of 115 F are a common thing in summer. These temperatures are however nothing in comparison to Sahara, were at Al-Azizia in Libyan Desert, temperatures shot up to 136 F in summer of 1919.
The winters show the same extreme features as those of summer. The winter of Moscow is well known. Even on the Indo Gangtic plains in North Central India, which are a typical continental location, subzero temperatures have been regularly recorded in winter. This is despite the fact that these are known in the world for their very hot summers.
So it concludes that large seasonal variations are a typical feature of continental regions. Next comes the discussions of rainfall, low relative humidity and extreme diurnal range of temperature.
Almost all continental region receive most of their rainfall in summer. At Moscow summer rainfall amounts to 60 percent of the total annual rainfall, at Lahore it amounts to more than 70 and at New Delhi it exceeds 80 percent of the total annual rainfall. The average relative humidity is everywhere very low throughout the continental region, except in Pakistan and India during monsoons. In Sahara desert, relative humidity as low as one percent has been recorded and even in India, in the pre monsoon months of April and May relative humidity of 15 percent and below is a norm in the afternoons.
The difference in the day time high and night time low -the diurnal range of temperatures- is very large in these regions. At Lahore, for instance, on a typical November day the day time temperatures are close to 88 F while nighttime low are typically 48 F. This show a difference of 40F in twenty four hours! It will be interesting to compare it with a location which is typically a marine i.e., Colombo. Here, the corresponding figures for November are 90 F and 80 F respectively -a difference of only 10 F in twenty four hours.
In short, the continental regions show an extreme tendency in their climate regime.