Tropical cyclone scales facts for kids

Tropical cyclones are powerful storms that form over warm ocean waters. They are known by different names around the world, like hurricanes, typhoons, or just cyclones. To help people understand how strong these storms are, scientists and weather experts use special scales to rank them based on their maximum wind speeds. These scales are important for predicting how much damage a storm might cause and for keeping people safe.

How Are Tropical Cyclones Measured?

Tropical cyclones are measured by how fast their winds are blowing. This helps weather forecasters and governments decide what warnings to issue and how to prepare. Different organizations around the world use their own scales to rank these storms. This can sometimes be a bit confusing because a "Category 1" storm in one place might not be exactly the same as a "Category 1" in another.

Why Do We Rank Tropical Cyclones?

Ranking tropical cyclones is super important for several reasons.

• Safety: It helps people know if they need to evacuate or take shelter. A higher category means more danger.
• Preparation: Governments and emergency services use the rankings to prepare resources. This includes sending out rescue teams or stocking up on supplies.
• Damage Prediction: Stronger storms cause more damage. The categories help predict how much destruction a storm might bring to buildings and nature.
• Communication: It gives everyone a clear way to talk about a storm's strength.

Different Ways to Measure Wind Speed

When we talk about a tropical cyclone's strength, we usually mean its "maximum sustained winds." This is the average speed of the wind over a short period, like one minute or ten minutes. The problem is, different weather organizations use different time periods for this average.

• Some use a 1-minute average.
• Others use a 10-minute average.

This difference means that a storm with the same actual wind speed might be given a slightly different category depending on who is measuring it.

The Saffir-Simpson Hurricane Wind Scale

The National Hurricane Center in the United States uses the Saffir-Simpson Hurricane Wind Scale. This scale is used for hurricanes in the Atlantic and eastern Pacific regions. It has five categories based on the hurricane's maximum sustained wind speed, measured over one minute.

• Category 1: Winds 74-95 mph (119-153 km/h). This can cause some damage to homes and power lines.
• Category 2: Winds 96-110 mph (154-177 km/h). Expect significant damage to homes and trees.
• Category 3: Winds 111-129 mph (178-208 km/h). This is a "major hurricane" with devastating damage.
• Category 4: Winds 130-156 mph (209-251 km/h). Catastrophic damage is expected, with many homes destroyed.
• Category 5: Winds 157 mph (252 km/h) or higher. This is the strongest category, causing extreme and widespread destruction.

How Australia Ranks Cyclones

Australia uses its own system for ranking tropical cyclones, which is different from the Saffir-Simpson scale. The Bureau of Meteorology in Australia uses a scale that also has five categories. However, their wind speeds are measured over a 10-minute average.

• Category 1: Winds 78-101 km/h. Minor house damage, some trees down.
• Category 2: Winds 102-125 km/h. Significant house damage, widespread power failures.
• Category 3: Winds 126-164 km/h. Structural damage to homes, large trees uprooted.
• Category 4: Winds 165-224 km/h. Significant roof and structural damage, very dangerous.
• Category 5: Winds 225 km/h or higher. Extremely dangerous, widespread destruction.

Different Names for Storms

To make things even more interesting, these powerful storms have different names depending on where they form in the world.

• Hurricanes: These are tropical cyclones that form over the Atlantic Ocean or the eastern Pacific Ocean.
• Typhoons: These are tropical cyclones that form over the western Pacific Ocean.
• Cyclones: This is the general term for these storms, but it's also specifically used for storms that form over the Indian Ocean or the South Pacific.

Even though the names and ranking scales can be different, the main goal is always the same: to help people understand the danger and stay safe from these incredible forces of nature.