Brown patch underside of Cattleya leaf

[philiplowrey]

Any idea of what this is? My Iwanagaara Apple Blossom has brown patches like this on the underside of 3 leaves. The tops of the leaves are completely unmarked. The patches are dry to the touch. This plant is outdoors, the brown patches all face the same direction (toward direct morning sun), and we have had some cold nights (around 40F) lately. I thought maybe sunburn, since the spots face the sun, but it is unlike any sunburn I've seen before.

[aliceinwl]

My Miltonia Sunset gets these when exposed to any temperatures below 50. Nothing can fix the damage that’s already occurred, but maybe start trying to put it somewhere warmer at night. The stretch from February to March seems to be hardest on my plants: most are spending nights in the garage now.

[philiplowrey]

Thank you! It puts my mind at ease to know what caused it. I’ll take precautions