How do hurricanes form?
Last Friday Bermuda had to face winds with speeds up to 110mph when hurricane Gonzalo hit its shores. The remnants of the hurricane reached Ireland on Monday night and will clear its way through the East coast of Great Britain at speeds of 70 mph right through to tonight (Wednesday).
Hurricanes are natural phenomena that have a devastating effect on humans and the environment. Hurricanes are tropical storms that are known as cyclones in the Indian Sea and the South East Pacific and typhoons in Japan and parts of South-East Asia.
Most hurricanes start with small wind disturbances in the Sahara, North Africa and with higher temperatures here and in the Atlantic between June and November, these months become a prime time for hurricanes to hit the East Coast of the US.
Hurricanes usually develop in tropical waters where a minimum temperature of 26°C is needed for formation. This makes the equator with its year round temperate climate a hot bed for hurricane formation. If the temperature during formation exceeds 28°C then we can expect to have a very severe hurricane on our hands.
Hurricanes form when the warm water on the surface of the Atlantic Ocean evaporates to form vapour which condenses to form water droplets. These then cluster to form thunderstorms and the change of state of the moisture releases energy that the hurricane uses for fuel.
As the water vapour travels to higher altitudes it meets colder air in the atmosphere and results in areas of high pressure above the thunderstorms. This imbalance with low pressures close to the surface of the Atlantic Ocean results in an increase in evaporation rate. More and more heated, moist air is drawn upwards as colder and dryer air from higher altitudes fall to lower altitudes, ominously increasing the size and power of the hurricane.
The rotation of the earth makes the air spiral and with this spiralling, the storm simultaneously spins around its own centre racking up outstanding wind speeds. When these speeds reach 75 mph it can be classified as a full blown hurricane. Interestingly the spin of the Earth results in Hurricanes spinning anti-clockwise in the northern hemisphere but clockwise in the southern.
The centre of the hurricane is called the eye, around which the eye wall develops. This is the most destructive part of the hurricane where the highest wind speeds of the entire hurricane are found. Hurricanes can be up to 400 miles in width with the eye reaching between 20 and 30 miles.
Luckily in Britain we don’t bear the brunt of most hurricanes, although weather reader Michael Fish did find himself red in the face when he claimed we had nothing to worry about before a devastating hurricane hit our shores in 1987. That was rare and we haven’t seen a storm like that since but it is important to recognise the damage it can do to countries across the world and provide aid where and when it is needed.