Leaves yellowing and drying out

[denisrosset]

I saved a few orchids from my workplace, and don't exactly know their species. I've neglected taking care of the problem below, which is now affecting a second orchid, so I want to check if it's infectious and how to care for it.

Here are two preliminary pics of the two orchids. I'd be happy to take more. During the summer, those orchids were watered by spraying them lightly everyday with a water bottle, and infrequent complete waterings, every 2-3 weeks (I usually leave them in a larger recipient to "bathe" and rinse the potting medium well). I stopped the water bottle spraying in September, roughly. They are located on a window, which may be a bit colder now.

The most recent affected:





The previously affected orchid:



Thanks for any pointers! I'm leaving the country soon and would love to address/identify the problem before potentially rehoming them.