Clouds and owls of Poland

The first stamp is part of the stamps issued on Clouds by Poland in 2016

A Cumulonimbus capillatus (Latin Capillatus, "hair") is a sub-form of cumulonimbus incus. It is a cumulonimbus cloud which has reached the level of stratospheric stability and has formed the characteristic flat, anvil shaped top with dense cirrus clouds which makes the cloud's top appear to contain hair-like structures.

Translations

Chmury = Clouds.
Cirrus, Cumulus, Stratus, Altocumulus, Cirrocumulus, Stratocumulus, Altostratus, Cirrostratus, Nimbostratus and Cumulonimbus are classifications of clouds.
Cb cap, CL=9, Cb mam, CL=9, Ci unc CH=4 and Cb cap arc, CL=9 are codings in the classification of clouds (i.e. CL for low level and CH for high level).

Western barn owl - Tyto alba 

With its ghostly appearance, spine-chilling shrieks and habit of roosting in abandoned builds, the Western Barn Owl has earned itself the nickname ‘ghost owl’. This mystical creature is the most widely distributed bird species in the world and it has been incorporated into folklore, with superstitions being passed from generation to generation. Western Barn Owls communicate by using a complex variety of sounds, with the most common being an eerie ‘schreeeee’ screech, usually made while in flight.Western Barn Owls are birds-of-prey and usually feed on small mammals; however, they occasionally feed on other birds, lizards and amphibians.Their main enemy is humans, who put out poisoned bait for rodents and if an owl happens to eat a poisoned rodent, it may eventually die of secondary poisoning.

Tyto means owl and alba means white in Greek ! The stamp is part of the owl minisheet issued by Poland in 2015

The other three are definitive stamps 

1 Zl - sunflower 

50 gr- cornflower 

15 gr - cranberry fruits ( updated - thanks Wojtek for the info )