The Compendium of Caraka 1.26.41

1.26.41

tatrāgnimārutātmakā rasāḥ prāyeṇordhvabhājaḥ lāghavādutplavanatvācca vāyorūrdhvajvalanatvācca vahneḥ salilapṛthivyātmakāstu prāyeṇādhobhājaḥ pṛthivyā gurutvānnimnagatvāccodakasya vyāmiśrātmakāḥ punarubhayatobhājaḥ //

There, the tastes consisting of fire and wind generally move upwards, due to the lightness and rising tendency of wind, and due to the upward burning of fire. Those consisting of water and earth, however, generally move downwards, due to the heaviness of earth and the downward-flowing nature of water. But those consisting of a mixture move in both directions.