INCREASED WILDFIRES FUEL MORE PYROCUMULONIMBUS CLOUD FORMATION

Why in the news?

Intense wildfires in the U.S. and Canada are generating more pyrocumulonimbus clouds, which can spark new fires and create thunderstorms, with their frequency increasing due to climate change.

INCREASED WILDFIRES FUEL MORE PYROCUMULONIMBUS CLOUD FORMATION - UPSCsource:wikimedia

Aboutv Pyrocumulonimbus Clouds Formation:

  • Occurrence: Created by intense wildfires or volcanic eruptions. Not all wildfires produce these clouds.
  • Process: Extreme heat from fires warms surrounding air, which rises and cools, forming a pyrocumulus cloud. If conditions persist, these clouds evolve into pyrocumulonimbus clouds.
  • Characteristics: Can reach up to 50,000 feet and generate thunderstorms but produce little rain.

Recent Trends:

  • Increased Frequency: Pyrocumulonimbus clouds have become more common. In 2023, 140 were recorded in Canada alone, compared to an average of 102 globally before 2023.
  • Previous Data: Prior to 2023, about 50 pyrocumulonimbus clouds per year were observed in Canada.

Climate Change Impact:

  • Role of Climate Change: Rising global temperatures and more intense wildfires may be contributing to the increased occurrence of these clouds.
  • Scientific Insights: More frequent fires create more opportunities for pyrocumulonimbus clouds, with atmospheric conditions playing a key role.
About Pyrocumulonimbus Thunderstorms:

  • Develop to altitudes over 16 km.
  • Spread fires through lightning, embers, and severe wind outflows.
  • Similar to normal thunderstorms with anvil-shaped clouds reaching high into the atmosphere.
  • Underneath, strong winds and erratic “downbursts” occur.

Smoke Plume:

  • Intense fire heat fuels rapidly rising air above the fire.

Plume Cools:

  • Smoke and ash reach high altitudes where the air cools.
  • Water vapour condenses into visible clouds.

Clouds:

  • Ash acts as condensation nuclei, helping water vapour form droplets.

Downpour:

  • Rain evaporates before reaching the ground due to fire heat.

Thunderstorm & Lightning:

  • Rapid formation increases the likelihood of lightning, similar to real thunderstorms.

Fire-Making Thunderstorms and Firestorms:

  • Emergence: Bushfires are now generating their own weather, worsening the wildfire crisis.
  • Dry Thunderstorms: Unlike regular thunderstorms, these are dry and produce only lightning, not rain.
  • Impact: Dry lightning can ignite new wildfires; strong winds from this system intensify existing fires.
  • Firestorms: Termed as “fire thunderstorm,” they are thunderstorms caused by the intense heat of bushfires.
  • Characteristics: Produce dry lightning, potentially leading to larger fires, driven by heat from the blaze itself