Tropical storms, which include hurricanes, cyclones, and typhoons, are powerful rotating low-pressure systems that form over warm tropical oceans.
They form strong winds and heavy rainfall.
Formation, Structure and Weather of Tropical Storms
Tropical storms form over the warm tropical oceans between 5° and 30° north and south of the equator. They are called different names depending on where they occur:
Hurricanes are tropical storms that form over the North Atlantic Ocean and Northeast Pacific
Cyclones are formed over the South Pacific and Indian Ocean
Typhoons are formed over the Northwest Pacific Ocean
Formation of tropical storms
Tropical storms require a specific set of environmental conditions to form and intensify. Let’s look at how they form:
Sea surface temperature – The ocean’s surface must be at least 27 degrees Celsius (80.6 degrees Fahrenheit). This warm water serves as a primary fuel source for these storms because it causes warm air to rise rapidly.
Warm rising air – This warm air rises, creating an area of low pressure beneath. The surrounding air rushes in to fill the low-pressure area, which in turn becomes warm and moist and rises. This process continually feeds the storm, causing the wind speeds to increase.
Formation of storm clouds – As the warm, moist air rises and cools off, the water vapour condenses to form clouds and rain. In a well-developed storm, the most intense rainfall and strongest winds occur in the eye wall, the ring of thunderstorms that surround the storm’s centre.
Storm’s eye – The air that has risen and cooled sinks at the centre of the storm, creating a relatively calm and dry area known as the eye. This area has light winds and little or no precipitation, and it is surrounded by the storm’s most intense weather.
Characteristics and structure of tropical storms
Tropical storms have the following characteristics:
Typically last for 7 to 14 days, although this can vary depending on environmental conditions
Cause heavy rainfall, which can often lead to severe flooding
These storms have high wind speeds, which can exceed 119 km/h (74 mph), powerful enough to cause a lot of damage
Intense winds generate high ocean waves, which can drive water towards the shore, causing devastating storm surges
The structure of a tropical storm involves several key components:
The eye – At the centre of the storm lies a relatively calm area known as the eye, which has descending cold air, low atmospheric pressure, light winds and an absence of clouds or rain.
The eyewall – Surrounding the eye is the eyewall, a zone where winds spiral rapidly. This area has the storm’s most intense winds and rainfall, making it the most destructive part of the storm.
Size variations – Tropical storms can vary greatly in size, with diameters ranging anywhere from 100 to 1,000 km (62 to 621 miles).