Reducing warping in 3D printing

Here I'm sharing some hints and tricks how to reduce the warping in 3D printing.

Everything started when I noticed that my MakerBot Replicator 2 printer on some days is printing excellent parts and the next day with the same file & settings, same filament and new blue tape is printing parts with noticeable warping.

I looked at different forums and read what people recommended for reduce the warping. After some experiments it came out that in my case the main problem was caused by the air conditioner and the opened window which is close to the printer. It seems that PLA printing doesn't like at all any air flows and cold temperature so I came with an idea to cover the printer with bubble foil which is hanging on stand nextdoor to the printer - see the pictures. After using this "Baldachin" the quality of the printed parts improved significantly (see attached picture of same parts printed with and without the cover).

In short - if having warping problems when printing with P