They are thunderstorm clouds (cumulonimbus) that develop due to intense heat generated by large wildfires, volcanic eruptions, or massive explosions

Formation

• A large wildfire or volcanic eruption generates intense heat.
• Hot air rises rapidly, carrying smoke, ash, and water vapour.
• Rising air cools and condenses into a pyrocumulus cloud.
• Continued uplift forms a cumulonimbus cloud.
• The cloud produces lightning, strong winds, rain (sometimes), and even hail.

Impact

• Injects smoke and black carbon into the stratosphere.
• Influences global climate by altering radiation balance.
• Reduces air quality over vast regions.
• Makes wildfire behaviour highly unpredictable.
• Lightning from the cloud may trigger secondary fires.

Source: The Indian Express