The phrase "rending air" refers to a sound or feeling of tearing or splitting, often used to describe intense emotions or a sense of tension in the atmosphere. Synonyms for this phrase could include "rending wind," "splitting sky," or "tearing atmosphere." Other options might be "cracking thunder," "shattering silence," "breaking storm," or "ripping sound." Each of these phrases evokes a sense of sudden violence or disruption, suggesting a feeling of chaos or turmoil. They could be used in a variety of contexts, from describing a dramatic moment in a story to capturing the emotions of a powerful performance or artistic expression.