Stair-rods
Rain "coming down like the bars of hell" --- in the recent discussion of this comparison, absent was any mention of why bars would be "coming down". The image is of a portcullis, handily defined by the OED:
"A strong barrier in the form of a grating of wooden or iron bars, usually suspended by chains above the gateway of a fortress, a fortified town, etc., and able to secure the entrance quickly by being released to slide down vertical grooves in the sides of the gateway."
We may understand that the rain in the comparison is falling suddenly, swiftly, and with implacable force.
Interesting! I can't wait until it rains so I can use that phrase.
I like the simile of 'stair-rods' - stair rods are metal rods of 1/4-1/2 cm diameter or so which secure carpet on stairways for safety. rain in droplets that thick appear to make rods as they pass the eyes, so it is a good comparison.
I was in Brussels a few weeks ago and there was rain like that - a virtual monsoon and I managed to capture some 'stair-rods' on camera.
L
The French say "Il pleut des cordes" ("It's raining ropes"), which I think is a good image too. (VSD)