What happens in nature during sunrise & sunset time whitch is also called transitional moment?

Question

sunrise sunset timings are called transitional moments or smallest circadium rhythm many changes take place in nature, visible changes is the ending of day & commencement of night vice versa ,it is said that even the breathing pattern of humans change during these timings also the sun rays which we recieve is pure with no heat element in it ,i wish to know more about them with authentic refrences from science journals, books; or sites etc , i will remain indepted to everyone who offers to assist ,thank you

Answer 1

Check out animal biology books.  Many animals show physical changes at these times as theya re usually rising or going to sleep around these times depending on whether they are day or nighttime creatures.

Answer 2

IT has been known for many years1 that there are anomalies in the number and strength of the distant atmospherics observed during the sunrise and the sunset periods. Investigations2 in this laboratory on distant atmospherics on high and medium radio frequencies showed unmistakable maxima during sunrise and sunset. Previously, Potter3 had observed similar effects. The effect of sunset on atmospherics was also reported by Subba Rao4. Besides Potter and Namba5, Khastgir6 recently offered an explanation of the sunrise and sunset effects observed. The object of the present communication is to show that on this theory a simple method can be devised for the location of a thunderstorm centre which gives rise to atmospherics by observing the time of occurrence of the maximum in the strength of the atmospherics, when the distant thunderstorm prevails over a period of time covering sunrise or sunset. The results of some directional observations of atmospherics at about sunset are also given in this connexion.