New Delhi: Even as Delhi struggles to breathe with its air quality persisting in the ‘very poor’ category, the authorities’ proposal for artificial rain to wash away pollutants is unlikely to be approved soon due to unfavourable weather conditions.

“It all depends on the IMD’s forecast regarding availability of required types of clouds for seeding, which does not seem favourable for at least a week. We will have to wait until the meteorological conditions are conducive for seeding," said Prashant Gargava, member secretary, Central Pollution Control Board.

A thick haze continued to envelop Delhi on Thursday, even as the effects of stubble burning in neighbouring states on air pollution in the capital was recorded to be minimal, according to the System of Air Quality and Weather Forecasting (SAFAR).

The forecast, however, indicated that the Air Quality Index (AQI) was likely to remain in the ‘very poor’ category for next two or three days due to high relative humidity and low temperature.

The current forecast indicates cloud formation on Thursday, but scientists at the Indian Institute of Technology (IIT), Kanpur, who have been working on an indigenous technology for seeding, highlight that the height of clouds is not optimum.

“These are ice clouds, which are quite high (above 6 km). The clouds should be at a height of 2.5 km to 4 km for seeding," said Professor S N Tripathi, head of the department of civil engineering and department of earth sciences, IIT Kanpur, “Nevertheless, if there is sufficient thickness in the cloud and it contains water and ice-crystals, trials can be attempted," he added.

The availability of required supercooled clouds, containing water and ice-crystals at a suitable height is a major challenge. According to scientists, the probability of such a cloud formation occurring during winter is low.

An aircraft has been secured from the Indian Space Research Organization (ISRO) and modified to install a seeding system and necessary clearances are being sought from different agencies for its use.

“We have approval from the Directorate General of Civil Aviation for the use of the aircraft, but it is subject to certain clarifications, which will be provided soon. The trials can be done as and when the environment ministry and the CPCB direct and meteorological conditions are favourable," Tripathi said.

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