Why does blowing air into aluminum coins turn up?

Aluminum coins are light and soft, with little stress and easy deformation. The airflow you blow at him can quickly reduce the pressure on him, and when the pressure below is greater than that above, it will turn over.

Aluminum orchid coins 1999 issued. By 2003, it had been released for five years, so it was called "Five Little Orchids". As an independent monetary system, the issuance of aluminum coins has always been the focus of people's collections in various countries. Since the First World War, all kinds of metal resources are in short supply, and countries have changed silver materials into aluminum materials or copper materials. Until now, aluminum and copper materials are the first choice for countries to issue metal coins. Aluminum coins are loved by quite a few countries.