Changing the bark of trees

As you know, wood during drying is breached, that is, it changes the form. As an open (hygroscopic) material, it reacts to the relative humidity of the air (we are reported in the weather forecast). It is because of the openness of a spruce bitch cannot respond to a change in pressure, but reliably reacts to changing humidity!
In 2001, we went to work through a spruce forest: rainy autumn, it darkens early, and so that in the dark not to accumulate on the branches, we broke down the dry bones in the head level at the head level. The rains ended, and after 2-3 days the bitches were again at the level of the eye! Then I made my first psychrometer from a fir bitch. The bitch chose a little, 110-120 cm long, two fingers thick. On the trunk, a lip of lying to the wall, Okaril. The psychrometer nailed on the wall where the straight sun rays do not fall, it does not grow rain and is well ventilated.
On the change in humidity, the bitch reacts with a delay: the shorter the bitch, the less this delay.
My bitch with a length of 5 cm is late with testimony for 2-3 hours. The end of the bitch "walks" along the wall up and down in the range of almost a meter! Over the years, they painted his moisturecy scale on the wall, and the testimony of my device is quite accurate!