Question

Why does Chennai has a lower annual range of temperature than lucknow

Answer 1

Chennai is located near the sea shore and hence gets moderating influence in temperature due to land and sea breezes while Lucknow is located in the interior part of the country away from sea influence and hence have more annual range of temperature than Chennai.
Hope it helps.

Answer 2

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Chennai experiences equable or oceanic climate because it has the influence of the sea, while Lucknow lies in the interior and experiences the continental climate/extreme climate. Hence the annual range of temperature is more in Lucknow than in Chennai.