Question

there is no major change in annual range of temperature of Chennai

Answer 1

It is so, because of moderating effect of sea i.e. continentality. Another major reason is its distance from equator.

Answer 2

Places situated near a sea or a large water body have a much smaller range of temperature variation over the year compared to places which are landlocked. For this reason Chennai, Bombay, Calcutta which are located on sea shore have less range of temperature variation. Large Water bodies heat up slowly and do not allow temperature to rise fast during summer and water also cools slowly during winter not allowing place located near a sea shore do not get very hot or very cold, displaying a very small range in which temperature varies from summer to winter