No. The weight of the cloud is not what forms the tornado. Tornadoes are form by interactions of wind currents within a thunderstorm.
Cumulonimbus.
IN simple terms, yes. Most tornadoes are produced by thunderstorms called supercells. There are more powerful than typical thunderstorm and are generally larger.
yes, some tornadoes are relatively small while others are huge
No. Hurricanes and tornadoes are two different types of storm. Size is not the only difference.
Vast interstellar clouds of hydrogen are known as "nebula."
Yes, there are huge clouds of hydrogen gas, called nebulae.
super cell
Of course tornadoes have been seen. They're not invisible. in fact, they're huge. You can see videos of tornadoes if you do a YouTube search.
When tornadoes are approaching they look like huge funnels. Tornadoes can approach an area very quickly You are advised to leave an hour before you can see the storm.
nebula
Cumulus.
Nebulas.