Kiedy Święta Agnieszka wypuszcza skowronka z mieszka?

We worship St Agnes, among other things, on 21st January. With the patroness of this day is attributed the proverb Święta Agnieszka wypuszcza skowronka z mieszka (St Agnes lets the skylark out of her sack). The author dwells on its genesis. It is usually still cold in Poland in the second half of January for skylarks to fly. There are other Polish proverbs (e.g. Po świętej Agnieszce widzimy muchy w chacie [After St. Agnes' day we can see flies in our house], on 5th February; Po świętej Dorocie wyschną chusty na płocie [After St. Dorothy's day the scarfs on the fence shall dry out], on 6th February). The proverbs seem to point that in the second half of January and in February it should be warmer. The evolution of our climate may account for the discrepancy between calendar proverbs and weather; another fact is that in the second half of the sixteenth century the Gregorian calendar replaced the Julian one. Historical testimonies and contemporary research on the climate in the past show that in the Middle Ages, i.e. during the formation of such proverbs as Święta Agnieszka wypuszcza skowronka z mieszka, the climate in Europe was warmer. According to the author, climatic changes may also shed more light on some old and ever discussed problems of the Slav researcher.