Looking through the haze

As is the norm in the winter season, large parts of northern India have come under the grip of intense fog, leading to low visibility. The India Meteorological Department tweeted on Thursday that very dense fog prevailed over Jammu, Punjab, Haryana-Chandigarh, West Rajasthan, Uttar Pradesh, and Bihar; dense fog was seen in Delhi, Uttarakhand, East Rajasthan, East Madhya Pradesh and Tripura; and moderate fog was observed in West MP, Odisha and Manipur. In certain parts of northern India, visibility dipped to as low as 25 meters while many other regions saw visibility dropping between 50 and 200 metres. In addition, the national capital has been witnessing minimum temperature lingering substantially below 10 degrees Celsius, and is expected to remain in the grip of severe cold for at least around a week. Unsurprisingly, daily life has been interrupted and transportation, mainly air flights and railways, have been substantially hit. Furthermore, the low visibility on roads present the risk of accidents. The fog, combined with deteriorating air quality, can also lead to a range of respiratory and health problems. Since low availability of sunlight affects the process of photosynthesis, the composition of oxygen and carbon dioxide gets affected in atmosphere. It is also hardly a secret that chilly fog in north Indian cities leaves the poorest and the marginalised more vulnerable than the affluent sections, with those residing on pavements bearing unbearable odds. However, irrespective of all this plight, one would argue, and rightly so, that foggy winter is a routine phenomenon, and hardly anything can be done to stop it. Nevertheless, it might be crucial to understand the science behind the formation of fog, and ensure safety from unwarranted mishaps at an individual level. The formation of fog involves complex atmospheric processes rooted in the principles of meteorology and physics. Fog is essentially a collection of tiny water droplets or ice crystals suspended in the air near the Earth's surface. Several factors contribute to its formation. The primary requirement is high humidity, where the air is saturated with moisture. As warm, moist air comes into contact with a cooler surface or encounters a colder air mass, it undergoes cooling. This cooling causes the air to reach its dew point, the temperature at which the air becomes saturated and water vapor begins to condense into visible water droplets. The cooling can occur through radiational cooling, advection (horizontal movement of air masses), or lifting of air over obstacles like mountains. The resulting fog may vary in density and persistence, ranging from light ground fog to dense, widespread fog that can significantly reduce visibility. In foggy conditions, it is essential to prioritise safety by focusing on visibility while dressing. Wearing bright-colored or high-visibility (fluorescent) clothes during the day can enhance visibility. Select reflective clothing can reflect car headlights, which is particularly effective at night. Vehicles should use bright headlights and rear lights, and pedestrians can boost visibility with additional lights on clothes or bags in both foggy and nighttime situations. Furthermore, city administrations should take proactive measures to ensure safety and well-being of those residing on the margins. It may also be noted that the crisis can be turned into an opportunity with the use of latest technologies. Fog catchers represent a remarkable solution to water scarcity, harnessing nature's own processes to provide a sustainable source of freshwater. Their success in various regions, from South America to Africa and Asia, underscores their versatility. The simplicity and cost-effectiveness of fog-catching technology make it an eco-friendly alternative, offering hope to communities grappling with limited access to freshwater. It is estimated that in India, 12.5 billion litres of water can be effectively collected through fog capturing in net screens (Singh, 2004). The United Nations Environment Programme has estimated that capital investment and other costs for this technology is generally found to be low in comparison with other conventional sources of water supply. The scientific community in India should explore the potential of such technologies to turn this annual crisis into an opportunity. While fogs cannot be stopped from occurring, there is a lot that can be done to minimise the adversities and problems inflicted by it.