How does tornado form

Most tornadoes form from thunderstorms. You need warm, moist air from the Gulf of Mexico and cool, dry air from Canada. When these two air masses meet, they create instability in the atmosphere. A change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere.

Rising air within the updraft tilts the rotating air from horizontal to vertical. An area of rotation, miles wide, now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation. If there are enough rising and sinking gusts, the air near the ground starts spinning.

This happens in the same way that figure skaters spin faster when their arms are drawn in rather than when their arms are outstretched. This is called conservation of angular momentum.

The rotating air moves horizontally across the land, and can be tilted vertically by the force of the rising, rotating air. That allows a tornado to form. As a thunderstorm develops, air rises, helping the cloud grow taller and taller. As warm air rises, clouds begin to grow taller and taller. This is the developing phase of the thunderstorm. You can see fluffy white cumulus clouds grow taller with your own eyes. This is before you see rain or hear thunder. As the clouds grow, you will notice the bottom of the cloud darkening.

You will many times see the very top of the cloud flattening out, creating an anvil shape that protrudes from the top of the cloud. This indicates very cold air at the top of the cloud and could be a precursor to the possibility of hail. When a thunderstorm becomes a supercell. As the storm matures, it could become what's known as a supercell. A supercell is a rotating thunderstorm. Cold air rushing out of the storm cloud, producing a gust front.

During this mature phase of the thunderstorm or supercell; heavy rain, lightning, hail and very strong winds are expected. Sometimes, you will feel a strong gust of wind a few moments before the rain arrives.

The weather forecast will give you a few hours' warning and some idea of what is coming. This information is thanks partly to hard-working satellites that keep a constant eye on the weather.

However, predicting tornadoes precisely is a different story. One minute it's just raining or hailing, and the next minute the roof or even the whole house is gone. If you were lucky, you and your family had a few seconds to find some shelter where you would not be picked up by the violent winds or seriously injured by large chunks of flying debris.

Where do these violent and unpredictable storms come from? Why do they destroy some buildings, but leave others nearby untouched? And is there any way weather forecasters could give people right in their path a little more warning? Certain conditions make tornadoes more likely. So, in that way, they are somewhat predictable. But no one ever knows when, where, how intense, and how many tornadoes a thunderstorm will create.