Why is fog increasing with every passing year in North India?......by Dr. Amandeep Aggarwal
Chandigarh: Fog and reduced visibility are the things that everyone has faced during the last 25 days and we often feel that extreme cold temperature and fog are increasing with every passing year.
Factors Contributing to increasing Fog in North India
· In the final days of 2023 and these initial days of 2024, an extensive layer of fog enveloped numerous states in the northern regions of India, presenting challenging conditions for both residents and travelers.
· Several areas in the northern part of the country reported frigid temperatures and thick fog throughout the last week of December. Late December 2023 weather reports indicated that minimum temperatures in Punjab, Haryana, and the northern extents of Rajasthan and Uttar Pradesh ranged from 6-9 degrees Celsius.
· The India Meteorological Department (IMD) reported minimum temperatures in New Delhi, south Rajasthan, and north Madhya Pradesh within the 10-12 degrees Celsius range during the same period.
· Concurrently, a substantial portion of North India encountered dense fog, significantly reducing visibility to as little as 50 meters for multiple days. Haryana, including Chandigarh, as well as isolated areas in Uttarakhand, Uttar Pradesh, Bihar, Rajasthan, and Madhya Pradesh reported fog with visibility dropping below 200 meters.
Understanding Fog:
Overview
Fog is a frequent meteorological occurrence. It comprises tiny water droplets formed when evaporated water cools and condenses. In simple terms, it resembles a dense cloud, positioned very close to the Earth’s surface.
For dense fog to materialize, temperatures must be lower, and an abundance of moisture should be present near the Earth's surface.
Formation
Fog materializes when there is a temperature contrast between the ground and the air. This is a common phenomenon during Indian winters, with fog forming when temperatures drop at night and in the early morning, condensing on aerosols in the atmosphere.
The combination of high humidity and a substantial presence of water vapor or moisture encourages foggy conditions. The cooling process plays a crucial role in fog formation.
Mechanism
A significant mechanism contributing to fog formation is known as Infrared Cooling. This typically occurs during the transition from summer to winter. In summer, the ground absorbs sunlight, warms up, and moistens the air passing over it. As cooler weather sets in, this warm, moist air encounters cooling processes, leading to rapid condensation of water vapor and the formation of fog.
Other Types
Another type of fog, called radiation fog, is common and occurs when a warm day with high humidity is followed by a rapid temperature drop. The specific type of fog, its duration, and its effects depend on various environmental conditions. For instance, there is a distinct type of fog that accelerates the melting of snow.
Why North India is Susceptible to Fog:
The entire Indo-Gangetic plains are predisposed to fog formation during the winter season due to the presence of all necessary conditions—low temperatures, minimal wind speed, moisture availability, and an abundance of aerosols.
Moisture-bearing winds, termed Western Disturbances, originating in the Mediterranean, bring moisture to Northern India. At times, the Arabian Sea contributes to increased moisture levels in the northern region.
Furthermore, the Himalayas in the north act as a barrier, hindering the eastward movement of fog over the plains, causing its concentration in the Indo-Gangetic region. the case of Delhi, pollutants such as particulate matter further contribute to the density, creating a phenomenon known as smog (smoke fog).
January 17, 2024
-
-
Dr. Amandeep Aggarwal, Family Physician, MBBS (Pb.), Cardiac Emergencies Course (Apollo Hospital)
dr_amanaggarwal@yahoo.co.in
Disclaimer : The opinions expressed within this article are the personal opinions of the writer/author. The facts and opinions appearing in the article do not reflect the views of Babushahi.com or Tirchhi Nazar Media. Babushahi.com or Tirchhi Nazar Media does not assume any responsibility or liability for the same.