All along from Chennai to Pondicherry, a thick fog enveloped the coast off Tamil Nadu. Ideal conditions developed for dense fog in Chennai.
Initially, a West (from cool land) wind commenced in the interim period from 5 am to 8.30 am, clashing with high humidity at 100%. The low/ideal velocity coming land breeze in the early morning hours met humid air, from a warm sea, sea temperature off Chennai was 29.3c. Land breeze could be around 20c then.
Perfect condensation was in place with a clear sky. As the fog formed, the winds died down at around 8 am and it was calm till 10 am. There was 0 - 0.5 kms visibility from 5 am to 9.30 am in Chennai. The fog, was maximum, with 0 visibility at around 8.30 am.