Ether (or space) has sound for its characteristic. Wind has touch for its characteristic. The characteristic of luminous bodies is colour, and water has taste for its characteristic.
शब्दलक्षणमाकाशं वायुस्तु स्पर्शलक्षणः। ज्योतिषां लक्षणं रूपमापश्च रसलक्षणाः॥