Question

why Tamilanadu have 2 rainy seasons in a year

Answer 1

Well during the period of june to sept when south west monsoon arrive at peninsular India it is bifurcated into two parts i.e arabian branch and bay of bengal branch so here it is also important to know that why TN remains dry during the onset of South west monsoon??there r two factor that are responsible for it:

1-Tamil Nadu coast is situated parallel to the Bay of Bengal Branch of south west mansoon

2-It lies in the rainshadow area of the Arabian Sea Branch of South west monsoon..

So when the sun starts shifting toward south,south west monsoon becomes weak as the low pressure shifts towards southward..or low pressure of Ganges valley in the beginning month of October covers the northern part of Bay of Bengal and by November it moves over Karnataka and Tamil Nadu.
So this retreating monsoon cause the rainfall in Tamil Nadu in winter.