Financial Daily from THE HINDU group of publications
Friday, Dec 30, 2005
Financial Daily from THE HINDU group of publications Friday, Dec 30, 2005 |
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Agriculture Agri-Biz & Commodities - Climate & Weather Fog means all-clear to rabi farmers even as pilots fret Vinson Kurian
Thiruvananthapuram , Dec 29 THE ubiquitous winter fog has come to be blamed for all that goes invariably wrong with airline operations in north India, but farmers in the region have the right reason to welcome the early morning nip this form of cloud brings to ground. This is because fog actually helps prevent the settling in of frost, a condition that rabi crops will do better without, says Dr Akhilesh Gupta of the National Centre for Medium Range Weather Forecasting (NCMRWF). Rabi wheat may be less sensitive to frost, but other crops such as mustard, gram and pulses are extremely sensitive, he told Business Line. Vegetation will not necessarily be damaged on a night where the air cools leaves below their freezing point. But once frost forms, it is possible that sharp ice crystals may damage leaf cells. Certain bacteria are known to be particularly effective at triggering frost formation. Fogs in the region are largely caused by advection (wind), a process in which moist air passes over cool ground and gets in turn cooled. Local winds blowing in from the hills (katabatic winds) slow down over the valley to produce convection, with the inherent moisture getting converted into fog. Katabatic winds are those that flow from high elevations of mountains, plateaus, and hills down their slopes to the valleys or planes below. Frequency of fog incidence in the north Indian belt has jumped by as much as 50 per cent since 1996, Dr Gupta said quoting studies. This is being attributed to the raised pollution levels, stronger advection pattern and increasing vegetation cover in Rajasthan. While largely discounting the role of pollution as a major causative factor, Dr Gupta said the increasing vegetative cover in Rajasthan has aided the propagation of cold wave conditions farther to the east. Meanwhile, the NCMRWF weather update said the existing western disturbance over north Pakistan and adjoining Jammu and Kashmir, the harbinger of cold wave conditions in the north, is now moving northeast and may become unimportant during the next 24 hours. Due to passage of this western disturbance, the night temperatures in a majority of places in the northern belt have been close to normal. However, some pockets in Haryana, Marathawada and interior Karnataka have reported cold wave condition during past 24 hours from the northwesterlies associated with the western disturbance. Barely 48 hours after the passage of above system, a fresh western disturbance of moderate intensity is seen approaching northwest India, which is likely to provide scattered to fairly widespread rain/snowfall over the hilly region and isolated to scattered rains in plains of Punjab, Haryana, north Rajasthan and West Uttar Parades on January 1 and 2, 2006. Considering the strength of the above system, moderate to heavy snowfall amounts are expected over isolated places in the hilly regions, especially in Himachal Pradesh and Uttaranchal, on these two days. Wednesday's upper air cyclonic circulation over south Tamil Nadu and neighbourhood has shifted to over Kerala and neighbourhood. The system may cause isolated rains in south Tamil Nadu and Kerala during the next 24 hours.
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