Thread by @biome_trust

What is the story behind the famous #Bangalore weather?

It goes back 3400 million years...🧵

Around 3,400 million years ago, the peninsular ‘gneiss’ came out and was cooled from volcanic activity.

This is what formed the city’s bedrock today. But the rock itself weathered and stored water in shallow aquifers.

Bengaluru as we know it today, settled at the fag end of the Deccan plateau, 900 metres above sea level.

This gave it the #pleasant climate that Bengaluru is famous for.

Let’s now skip to 88 million years ago. >>

The sub-continent that is now #India, started drifting north to meet the Asian continent. The Himalayas are the creation of this slow movement of India into #Asia.

But a piece of the Western Ghats remained in #Madagascar from which India separated in its northward journey. How?

India, #Africa, South America, Madagascar, #Antarctica and #Australia were lumped together in a single landmass called Gondwana land, which eventually started breaking up into multiple pieces.

Madagascar was attached to India's present-day western coast. It split from the Indian plate almost 90 million years ago.

This place, where the Indian plate broke, is the Palakkad Gap.

Here, the Western Ghats dips to about 300 meters above sea level. From this gap, humid winds rush in from the Arabian Sea and swing northwards.

In April and May they also bring the famous ‘office showers’, around 5 PM to the city.

So it is the #winds from the Palakkad gap that cause #Bengaluru’s bi-modal rainfall: with one peak in May and the other in September-October.

Typically, the city receives a total of 970 mm of rainfall, much higher than its surrounding areas.

This thread has compiled a few excerpts from @zenrainman’s article in @the_hindu: 'Bengaluru’s water story: can the paradise be regained?'

Read the full article:
thehindu.com/news/cities/ba…