Issuu on Google+



Step 2 The Four Conditions Now you have a basic understanding of how the world and it’s weather works, it is time to begin looking at the conditions in which tropical storms can form in. There are four key factors. Without these, a tropical storm is unable to grow or even form successfully.

Number One: A tropical storm can only form in or over an ocean, it can never form on land. The ocean is the only place with all of the correct comp-onents to brew the perfect storm.

Number Two: Storms form in warm, humid

Common places to find a tropical storm include: the Pacific, Atlantic and Indian ocean.

The most suitable and appropriate place for a storm to form is the tropics. Hence the term ‘tropical storm’.

areas, typically 26 degrees celsius or over. This means they cannot form in the colder areas of the world such as the north or south poles.

Number Three: Lots of moisture will be required in the formation of a tropical storm. Fort-unately there is plenty of water available in our oceans located within the tropics.

Number Four: The final condition, required is

wind direction. To allow vapour and clouds to rise or form a ‘tower’ all wind must be blowing in the same or similar direction. If wind patterns do not match, clouds will not be able to tower and a storm cannot be formed.

Step 3 Formation of the Storm Once all of the four conditions are met the storm can now start forming.



Over the ocean 26 degrees or warmer Lots of moisture Similar wind patterns

Part 1: Evaporation


When the sun shines throughout the tropics, its rays hit the oceans surface. The energy from the sun is then transferred to the surface in the form of heat. Scientifically speaking, as the water heats, the oxygen and hydrogen molecules will gain energy and begin to move around faster and with greater force. When the energy is high enough the water molecules will gradually break apart. This turns the water from a liquid into a gas: water vapour. This process is called evaporation.






Step 4 Rising Vapour After the water begins to evaporate, water vapour can start to rise. People typically assume that clouds are a form of water vapour however, this is incorrect. Clouds are actually made up of liquid water. Water vapour on the other hand, is a transparent gas (meaning we are unable to see it). It weighs less than air, causing it to rise up into the atmosphere. Due to the coriolis force, as vapour rises it also begins to spin. The direction of which depends on whether it is in the southern (clockwise) or northern (counter-clockwise) hemisphere. KG

Temp (C) Density














*these statistics are taken from air at a standard atmospheric pressure

Step 5 Condensation

As the water vapour continues to rise higher and higher, it will eventually begin to cool, forming clouds. This is a process called condensation. So how exactly does it work?

FUN FACTS: Clouds form in a place called the troposphere Clouds have known to form on other planets including Jupiter and Venus

Clouds are a large collection of very tiny water droplets. These droplets are so light that they are able to float in the air. When our warm air and water vapour rises it expands and slowly cools. Cool air cannot hold as much water vapour as warm air, so some of the vapour condenses. When this happens the vapour turns into small water droplets. It is these droplets of water which then come together, forming a visible cloud.

Rising Vapour


- usually not seen as it is a transparent gas.

- water droplets gather and mix with air.


- vapour cools and turns into tiny water droplets.

Formation of Clouds

- clouds form from these thousands of tiny little water droplets.

Step 6 Low Pressure Pressure is quite hard to understand so in simpler terms it is essentially the weight of the air. Pressure is the amount of weight the atmosphere presses down on the Earth’s surface. Low pressure is found higher up in the atmosphere, such as in mountain ranges, as there is less weight pressing down. Higher pressures however, are found lower down, near sea level. This is due to the fact there is more atmospherical weight pressing down on it. In terms of our tropical storm, towers of cumulonimbus clouds form high up in the atmosphere. An intense low pressure is present here and so forth encourages violent winds to brew and begin to spin.



Step 7 Losing Energy Westerly winds will eventually push a tropical storm onto land and it is here where it will eventually lose energy and die. Up until this point the storm has been able to use the ocean as an ‘engine’ to fuel and feed it as it grows. When a storm first hits land it typically has devastating effects, causing thousands of casualties and damage. Now on land though, it no longer has an engine to drive it. The 4 required conditions can no longer be met and so the storm slowly loses energy.

Tropical Depression

Tropical Storm




Life Cycle of a Tropical Storm