When there is a very low voltage (AC), even for a compact fluorescent lamp (CFL), it glows very dim (orangish in color) at the beginning of the glass but when I hold the glass just for a second, it starts glowing as usual (generally white in color, don't know what your's is) though a very little bit dimmer than its original capacity. So, I want to know why it happens, i.e. it starts glowing at the same voltage when we touch it (the one I am trying is rated 220V, AC Current freq here is 50Hz, power required doesn't matter as it happens with all of them, voltage is ~30 in my case but it may differ in yours). If it's related to body-heat (because I think so), why does it just keeps glowing continuously even if we don't touch it after that?
Sounds like you are "striking an arc" with static electricity by touching it - setting off the gas to become a "electrically conductive medium" which is how a fluorescent bulb normally works. The glow is maintained by the low AC voltage at that point - just not as well as the correct voltage.
Interesting observation, I will take a guess, since I cannot reproduce. AFAIK, those kind of lights operate on the principal of avalanche. The system has two equillibria, one in which the population of electrons is not enough to trigger an avalanche in which the collective motion of electrons are enough to create a bright light, and the other that is enough. I think bu contact, either by the warmth of your hand, or better contact with the conductors due to jiggling, you move the system from one equilibrium to other. And after that, there is no turning back, because the electron motion is enough to sustain operation.