- The air near the surface cools at night as a result of the land surface cooling.
- Fog forms when water vapour in the air condenses because cooler air cannot hold as much moisture as warmer air.
- Early in the morning, when the temperature is at its lowest, fog starts to form.
- Two of the most important conditions for the formation of fog are moisture content and a drop in temperature.
- There can be “high spatial variability” in fog, and temperature, wind, and humidity can all affect how thick the fog is.
- Because of the increased humidity, areas close to bodies of water, for example, may experience denser fog.
- The months of December and January see significant, weeks-long periods of heavy fog, with the Indo Gangetic Plain being most susceptible to these occurrences.
Types of fog
- The area covered and duration of advection fog are larger.
- It originates from the condensation of water vapour on a cool surface by warm, humid air.
- It happens at the interface of cool ocean water and warm tropical air.
- When the wind blows in the proper direction, sea fog spreads across coastal regions.
- is the result of mountains blocking the escape of dense air.
- For several days, fog is trapped at the valley’s bottom.
- is result of liquid droplets freezing on solid surfaces.
- On cloud-covered mountaintops, it happens.
- The Indo Gangetic Plain does not contain them.
Conditions Favouring Fog over North-western India
- In northwest India, the temperature has started to drop.
- Six degrees Celsius is the lowest minimum temperature Delhi has seen this season.
- Recent reports of extremely low minimum temperatures over Punjab, Haryana, and portions of Rajasthan indicate the presence of cold wave conditions.
- There is a lot of fog over the Indo Gangetic Plain as a result of the temperature dropping, moisture, and light winds.
Effect of Western disturbances:
- Winds carrying moisture are brought to northwest India by western disturbances, which are storms that originate in the Mediterranean Sea.
- This may cause the region’s moisture content to rise.
- Local moisture sources such as soil moisture and river water vapour can also produce fog in the absence of western disturbances.