Heart rate, color, irritability, muscle tone, and breathing
Once entering the atmosphere the heated up water vapor (that's the process of evaporation) cools back down (the atmosphere is cooler than the Earth you see). it makes clouds Their it will condense until it's heavy enough to fall to Earth as precipitation!
When conducting legal experiments on animals, a researcher needs to obtain consent from the INSTITUTIONAL RESEARCH BOARD.
Each research institution has research board which sees into uses of animals for research purposes, consent must be obtained from the board before experiments involving usage of animals is carried out.
The answer is that the equatorial regions receive sun rays closest to the vertical (direct rays) because of their position relative to the equator where the tilting of the earth only mildly affects the climate. The climate along the equator changes very little through out the year and has summer like conditions for most of the year.
However the other regions may receive direct sun rays but for far more limited periods. In the months of July and August (summer months), the northern hemisphere is tilted towards the sun and receives the most direct rays. The opposite occurs in December and January when it is tilted away from the sun and thus winter sets in, whereas the southern hemisphere is at this time tilted toward the sun and receives the most direct sun rays.