seems to always happen when its cold
You see, the black hole consumes ANYTHING it sucks, even light. If the gravitational pull is so great, it can even pull light back. So, even the earths gravity effects light, but effects very little. The less gravity, the easier the light travels, works the same with people.
The first answer is very informative however I would like to add Wheel Impact Load Detectors aka WILD. These are used to detect wheels that have flat spots on them from skidding (too much brake or hand brake left on) or wheels that have chunks broken out of them. Both these defects can cause severe track damage and/or derailment.
Did / . This will absolutely save yourself!
Because Light (photons) has energy hc / (Lambda) and momentum h /(Lambda). {(Lambda) wavelength; h Planck's constant 6.6262 X 10^-34 Joule S}
