Understanding of the Atmospheric Boundary Layer (ABL) is imperative in the arena of the monsoon field. Here, the
features of the ABL are studied employing Conserved Variable Analysis (CVA) using equivalent potential temperature
and humidity. In addition, virtual potential temperature and wind are used during active and weak phases of
monsoon. The analysis is carried out utilising the radiosonde observations during the monsoon months for two stations
situated in the west coast of India. All these parameters show considerable variations during active and weak monsoon
phases in both the stations. The core speed and core height vary with these epochs. The core speed is found to be more
than 38 knots in the active monsoon phase around 1.2 km over Trivandrum and around 2 km over Mangalore. But
during weak monsoon phase the core wind speed is decreased and core height is elevated over both stations. The wind
direction shows an additional along shore component during weak monsoon period. The Convective Boundary Layer
(CBL) height shows increase during weak monsoon phase over both stations due to less cloudiness and subsequent
insolation. The CBL height during the southwest monsoon is more over Mangalore and is attributed by the orographic
lifting in the windward side of the Western Ghats while the influence of the Ghats is less over Trivandrum.