That's The Reason Why Poem by Bernard F. Asuncion

G-uess that's the reason why
E-vening passes from view;
L-etting the darkness turn
I-nto shine beneath the blue.
C-learly that's the reason why the morning has to break;
A-llowing the dusk to fade for dawn to have the chance to take.

C-learly that's the reason why
A-nother day will surely shine;
P-aving the way for the sun to rise,
R-ainy weather turming fine.
I-nspiring lines are written,
C-learly that's the reason why;
H-appy birthday to you
O-n seventh morn in July.

A-fter the storm has gone
N-ew light comes from the sky;
A-lmighty's will has ruled,
C-learly that's the reason why.
I-nto the sea the river flows, like the falling tears that I cry;
N-ature's way of introducing God, no doubt that's the reason why.