We don't know everything about tropical cyclones. We don't know why they form or why they last so long, but we do know that they form over warm ocean water, in an area of low pressure. These conditions are generally found within 10-20° latitude on either side of the equator, where water temperatures of at least 26°C occur, making the oceans around the northern half of Australia perfect.

Resembling a giant whirlwind, the winds of a cyclone in the southern hemisphere spiral clockwise towards its centre, where they rise up to the top of the cloud mass and spill over into the upper atmosphere. The cyclone usually grows in size and strength as it travels at moderately low speeds of 20-25km/hr.

The sun's heat evaporates the ocean's warm water, with the moist air cooling and condensing as it rises, ultimately producing torrential rain. These rains can cause enormous damage through flooding and landslides.

How much damage will a cyclone cause?

The extent of the damage depends on the force of the winds, the cyclone's path, what it picks up along the way, and how well prepared we are. Remember, whatever it picks up, it throws down later with enormous force (and that could be your roof).

Australia's most destructive cyclone, Tracy, which destroyed much of Darwin in December 1974, recorded winds in excess of 217km/hr, with 195mm of rainfall recorded in less than nine hours.

To find out what to expect from different cyclone categories, click here.

Beware the eye of the cyclone

If you've ever seen images of cyclones, they all look different. But inside, they all look much the same. The centre of the cyclone, or the eye, is the point where the pressure is at its lowest.

The eye is commonly 40km in diameter, but can reach up to 100km across. Unlike the rest of the cyclone, in the eye, light winds and clear skies prevail. But beware, this can be deceivingly dangerous!

If the eye passes directly over you, you'll experience a sudden lull in wind, which may last for a few minutes or up to two hours. Hence, people often think the cyclone has passed - but that was only half of it. The other side of the cyclone then strikes, with winds blowing again, but this time from the opposite direction.

The area immediately surrounding the eye is called the wall. This dense ring of cloud reaches upwards of 15km high. It marks the region of the cyclone's strongest winds and heaviest rainfall, and causes most of the damage.