As our world warms and succumbs to the repercussions of pollution, scientists have projected an expected rise in the frequency and intensity of lightning. Data reveal startling statistics of over 2500 people losing their lives annually to lightning strikes just within India’s borders. It’s crucial to critically examine the factors that contribute to this, namely urban heat and pollution.
The Role of Urban Heat
For cities evolving at a rapid pace, concretization is creating a noticeable increase in temperature – turning urban areas into veritable heat sinks. A decrease in open, green spaces exacerbates the situation further. The resulting warm air ascends from cities, getting replaced by incoming cooler air, leading to instability if enough moisture is available. This triggers the formation of convective clouds, often linked with increased lightning activity. A clear example of the urban heat island effect is seen in Delhi where a whopping five-fold rise in pre-monsoon lightning was observed due to this very phenomenon.
Global Warming’s Impact
A domino effect of the warming climate could result in stronger thunderstorms. The interpretation of recent findings puts forth a scenario wherein global warming has a direct correlation with the potential severity of thunderstorms.
Pollution and its Part
Not to be overlooked, high concentrations of aerosols (pollutants suspended in the atmosphere) also boost the instances of lightning. With a notorious ability to shrink cloud droplets, these pollutants facilitate the conversion of more water into ice. Consequently, there’s an increase in the electrical conductivity of clouds by 50%. Studies have found that pre-monsoon rainfall is usually accompanied by more lightning flash counts than during the monsoon, largely attributed to pollution levels.
| Aerosols’ Impact | Pre-monsoon | Monsoon |
|---|---|---|
| Cloud Droplets Size Reduction | High | Low |
| Lightning Counts | High | Low |
| Pollutant Concentration | High | Low |
Understanding Lightning
Now that we have studied the contributing factors, let’s proceed with what exactly lightning is. Simply put, it’s a visible discharge of electricity occurring when a region of a cloud acquires an excess electrical charge (positive or negative). This charge is sufficient to overcome the resistance of air. Most often associated with cumulonimbus clouds, it can also occur in stratiform clouds, snowstorms, dust storms, and at times even in the dust and gases emitted by erupting volcanoes.
What Triggers Lightning?
Lightning gets triggered when regions within the cloud develop excess positive and negative charges. These charges primarily reside on water drops, ice particles, or both, leading to sudden and violent electrostatic discharges within the cloud that create the visible lightning.
Urban Heat Island Effect: An Overview
Labeled as the “urban heat island effect”, the elevated temperatures in urban areas as compared to rural, less developed areas is a result of urban development. The climatic differences observed in urban areas versus less developed regions attribute to variations in air temperature, humidity, wind speed and direction, and precipitation amount. These are largely due to the modification of natural terrain through the construction of artificial structures and surfaces. This phenomenon has a significant role in affecting weather patterns and lightning frequency. This is our reality as global warming and pollution continue to rise, leading to an inevitable increase in lightning occurrences.
