A storm is a storm with rain and wind, right? Yes. Then why call one storm tropical compared to subtropical? An encounter with a named tropical system would be typically more damaging with a purely tropical system since the winds are often much higher because of the way the storm is built.
Tropical systems develop over warm water with light winds aloft. As long as these two conditions are not disturbed, thunderstorms can organize and grow into powerful hurricanes in humid tropical environments. At their core, is warmer air released from thunderstorm clouds.
Subtropical storms, on the other hand, are cold-core systems, meaning that they derive their energy from the temperature difference between the warm ocean and the cooler air above it. These systems often stay below hurricane strength because of the hostile high winds aloft that keep the storms spread out far from the center of the storm. When they do become hurricanes the transition to a warm core, takes time.
Another difference between the two types of storms is their structure. Tropical storms have a well-defined center and a symmetric wind field, with the strongest winds located near the center. They usually develop a clear eye in the middle when winds increase over 74 mph.
Finally, tropical systems tend to produce more rain than subtropical storms. This is because tropical storms have a more efficient mechanism for lifting warm, moist air into the upper atmosphere, where it condenses and forms clouds and rain.
Subtropical storms, on the other hand, have a less well-defined center and a more asymmetric wind field, with the strongest winds located farther away from the center. This gives the system a lopsided appearance like a coma shape on the satellite.
📹 WATCH: What is a subtropical storm?
A tropical storm over cooler ocean water often evolves into a subtropical storm, pushing its peak winds well away from the center. Subtropical storms that drift over warmer water can consolidate their wind field and become tropical storms.