為何英文中傾盆大雨叫做下的阿貓阿狗(It rain cats and dogs),
(1) It seems that cats were at one time thought to have influence over storms....
and that dogs were symbols of storms,
often accompanying images and descriptions of the Norse storm god Odin.
So when some particularly violent tempest appeared,
people suggested it was caused by cats (bringing the rain) and dogs (the wind).
(2) 這個片語初次出現，是在Jonathan Swift在1738年所著的
「A Complete Collection of Polite and Ingenious Conversation」：
I know Sir John will go, though he was sure it would rain cats and dogs.
(4) At this period the streets of British towns were so poorly constructed
that many cats and dogs would drown whenever there was a storm;
people seeing the corpses floating by would think they had fallen from the sky.
(5) There are other similes which employ falls of improbable objects as
figurative ways of expressing the sensory overload of noise and confusion
that can occur during a violent rainstorm....
It's probable that the version with cats and dogs fits into this model,
without needing to invoke supernatural beliefs or inadequate drainage.
以上皆為關於「rain cats and dogs」之典故，敬請參考。