I have performed some tests and have come to understand that the Storm has some sort of sensor that detects sunlight and/or bright light. I wondered why my screen in portrait mode would dim and light up at random moments but then, sitting in my desk with my window open, I put the blackberry under my desk where there is hardly any light and noticed that my screen would dim. Then I placed the Storm on my table where the sunlight shined, then i noticed the screen light up. While performing these tests I constantly touched my screen so that the Storm would not go into sleep mode.
In a dark environment the back light would not have to be lit up to its max for one to read the screen but in a well lit environment the intense light would wash out the light coming from the screen. If anyone out there is willing to perform more comprehensive tests please confirm my findings.