Last Updated:
Winter rainfall has a distinct impact on temperature. While winters are generally dry, rain can influence the cold in a few ways.
People visit India Gate amid rain, in New Delhi, Friday, December 27, 2024. (PTI Photo)
As winter progresses, many regions across the country including Delhi NCR experience occasional rainfall. While the effects of summer rainfall are widely understood – offering a temporary reprieve from the sweltering heat – winter rain behaves differently, often sparking confusion about its impact. Some people claim it lessens the cold, while others argue it intensifies it. But what does science have to say about how winter rainfall affects the weather?
Why Does It Rain In Winter?
Rainfall during the winter months is relatively rare and is not connected to the monsoon season. Instead, it occurs due to a weather phenomenon known as the Western Disturbance. These disturbances are characterised by winds coming from the northwest, originating from the Mediterranean region. These winds interact with the atmosphere over the Indian subcontinent, creating pressure conditions conducive to rain. These disturbances bring both precipitation and changes in weather patterns, affecting regions like the northern and southern part of the country.
Impact on Temperature: Does the Rain Make It Colder?
Winter rainfall has a distinct impact on temperature. The cold air from the snow-capped Himalayan regions typically drives down temperatures across the plains. While the winter season is generally dry, rain can influence the cold in a few ways. Rainfall often causes temperatures to drop further in the short term as the combination of cooler temperatures and increased humidity from the rain can create a stronger sense of cold. This dual effect – lower temperatures and higher humidity – amplifies the chilly conditions.
Interestingly, the impact on temperature also depends on the severity of the cold. In regions with extreme cold, such as the Himalayan foothills, the rain can slightly reduce the intensity of the cold. On the other hand, if rainfall occurs in areas that are already cold but not excessively so, it may have a warming effect. For example, light rain in extremely cold areas might prevent the temperature from dropping even further, offering brief relief.
Does Rain Influence Fog And Visibility?
One of the most noticeable effects of winter rain is the change in fog conditions. Rain increases the humidity in the air, which can make fog more dense, particularly in northern areas. In plain areas where humidity levels are already high, rainfall can worsen fog, reducing visibility significantly. Conversely, in regions where fog is already present, rain can help dissipate it, clearing the air somewhat before new fog forms.
How Rain Helps In Reducing Pollution
In cities like Delhi, where air quality often plummets during the winter months due to the accumulation of pollutants, rain helps cleanse the atmosphere by washing out dust, smoke, and other particulate matter. This leads to a temporary improvement in air quality, reducing the severity of air pollution. This is especially beneficial during winter, when conditions like temperature inversion can trap pollution near the ground, making the air even more hazardous to breathe.
Winter Rain and Cold Waves
Although winter rainfall can increase the cold in the short term, it does not typically lead to the onset of cold waves. A cold wave, characterised by extreme cold temperatures and prolonged freezing conditions, is usually triggered by snowfall in the Himalayan region. While rainfall may affect the intensity of these waves, it does not directly cause or end them.
