mushroom cloud
noun [ C usually singular ] uk/ˈmʌʃ.ruːm ˌklaʊd/ us/ˈmʌʃ.ruːm ˌklaʊd/
（尤指核爆炸后形成的）蘑菇云
a very large cloud of dust that rises into the air in the shape of a large mushroom, especially after a nuclear explosion
The mushroom cloud over Hiroshima is a horrific image of war. 广岛上空的蘑菇云是战争恐怖景象的写照。