met·a·chro·ma·tism 
(mĕt′ə-krōmə-tĭz′əm)
(mĕt′ə-krōmə-tĭz′əm)n.
A change in color caused by variation of the physical conditions to which a body is subjected, especially such a change caused by variation in temperature.
met′a·chro·matic (-mătĭk) adj.