<p>New Delhi: A thick layer of fog enveloped several areas of Delhi for a third consecutive morning, leading to 51 trains being delayed, officials said on Sunday.</p>.<p>The Met office said there was zero visibility at Palam between 4 am and 7:30 am. On Saturday, Palam had recorded a nine-hour spell of zero visibility.</p>.<p>At Safdarjung, the visibility dropped to 0.50 metres at 5:30 am.</p>.<p>General visibility at the Palam and the Safdarjung airports was reduced to zero in very dense fog at 7:30 am.</p>.At 9 hours, Delhi sees season's longest zero visibility spell as dense fog shrouds city.<p>In a related development, the national capital's air quality was in the 'very poor' category, with an Air Quality Index (AQI) reading of 372 at 9 am, according to Central Pollution Control Board data.</p>.<p>An AQI between zero and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.</p>.<p>The minimum temperature settled two notches above normal at 9.4 degrees Celsius. The humidity level was recorded at 95 per cent at 8:30 am.</p>.<p>The Met office has predicted dense to very dense fog during the day. The maximum temperature is likely to settle around 18 degrees Celsius.</p>
<p>New Delhi: A thick layer of fog enveloped several areas of Delhi for a third consecutive morning, leading to 51 trains being delayed, officials said on Sunday.</p>.<p>The Met office said there was zero visibility at Palam between 4 am and 7:30 am. On Saturday, Palam had recorded a nine-hour spell of zero visibility.</p>.<p>At Safdarjung, the visibility dropped to 0.50 metres at 5:30 am.</p>.<p>General visibility at the Palam and the Safdarjung airports was reduced to zero in very dense fog at 7:30 am.</p>.At 9 hours, Delhi sees season's longest zero visibility spell as dense fog shrouds city.<p>In a related development, the national capital's air quality was in the 'very poor' category, with an Air Quality Index (AQI) reading of 372 at 9 am, according to Central Pollution Control Board data.</p>.<p>An AQI between zero and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.</p>.<p>The minimum temperature settled two notches above normal at 9.4 degrees Celsius. The humidity level was recorded at 95 per cent at 8:30 am.</p>.<p>The Met office has predicted dense to very dense fog during the day. The maximum temperature is likely to settle around 18 degrees Celsius.</p>