Shiva is an exponent and proponent of art forms, especially dance. His dance Tandava is well known and the pose of his standing on his right foot with the left foot across in air, with his hands in beautiful mudras is synonymous with India. This explicit pose of poise and grandeur is what Nataraaj is depicted as.
Shiva as the Supreme manifests in everything from the minutest of elements to mightiest of forces in the universe. Its His dance that is reflected in the energy patterns, the sync of breathe the grace of wind, the flow of water, the lapping of the sea, the still grandeur of mountains, the beating of hearts, and everything.
Shiva creates (as Brahma manifestation) by being the creator of the Naad, Roopa and Svaras. Shiva sustains (as Vishnu manifestation) by maintaining the rhythm of the universe and balancing it. Shiva destroys (as Shankara manifestation) by his force of destruction giving birth yet again to new. Thus sustaining the cycle of life.
If we look closely everything around us vibrates in Shiva’s tandem.
He is the Supreme One with celestial Dance wherein Shiva and Shakti unite, manifest and exult!
Clearly Shiva is Nataraaj.