A hurricane normally takes many days to form. A hurricane may build in as little as 48 hours, or two days. If a thunderstorm cluster already exists, it may just take a day. No matter how long it takes, though, once it forms, it is still able to cause tremendous damage.
Hurricanes are large storms that can travel across oceans. They are formed when air over warm waters becomes more buoyant, causing it to rise. The rising air then meets cooler air from the higher altitude which causes the air to collapse and become dense. This sudden drop in temperature causes raindrops to form crystals that grow larger until they fall to the ocean's surface. These crystals are called "salt crystals." When many salt crystals collide with the surface of the water they create a dusting of white powder that is visible from space today known as a "hurricane track."
Most hurricanes start out as tropical storms, which are similar to hurricanes but not as strong. Tropical storms are caused by clouds with low pressure associated with them. As these clouds pass over warm water they absorb heat which creates more intense clouds that may develop into a depression or an intensification. At this point, the storm has the potential to become a hurricane. Once a depression is recognized by the National Hurricane Center it will be given a name.
A hurricane may be tracked once it has developed. Typically, scientists can forecast its route 3-5 days in ahead. A hurricane's likely path is typically shown as a cone that shrinks over time as the forecast error lowers. Occasionally, storms change course or intensify after making landfall.
Hurricanes are large systems of rotating air currents called cyclones. They are characterized by high wind speeds and heavy rainfall. Hurricanes form when deep layers of the atmosphere known as the troposphere meet at 20 degrees north or south of the equator. The combination of these two atmospheric conditions results in a low-pressure system that draws more air into itself until it reaches the critical point where there is no place else to go. At this point, it begins to rotate like a storm cloud.
Scientists first learned about hurricanes from observations made by sailors. Because hurricanes cause such severe damage at their reach, many civilizations have tried to predict their arrival. Over time, scientists have improved their knowledge of hurricane behavior so they can make better predictions. Today, computer models help scientists learn how hurricanes form and what areas of the world are at risk of receiving strong winds and heavy rainfall.
In 2005, Hurricane Katrina was one of the most devastating hurricanes to strike the United States. When it made landfall near New Orleans, it was a category 4 storm with winds exceeding 115 miles per hour.
It frequently begins as a single or group of thunderstorms in a process that can last anywhere from a few days to more than a week. Similarly, the life cycle of a tropical cyclone (from tropical depression to tropical storm to hurricane to death) can be as short as a day or two or as lengthy as a month. A tropical cyclone's lifetime is usually about 10 to 14 days.
The average lifespan of a tropical storm is about six hours. The average lifespan of a hurricane is about three days.
These figures should be considered approximate because they depend on many factors such as strength, moisture content, structure, proximity to land, etc. Also, most tropical storms and hurricanes develop in the Atlantic Ocean but some develop in the Pacific Ocean. Tropical storms and hurricanes that form in the Gulf of Mexico are classified as extratropical when they reach land.
Extratropical storms have the same general characteristics as tropical ones but they do not experience any major temperature changes which would indicate their re-entry into the troposphere. Instead, they slowly lose energy as they move away from the equator toward the poles.
When they reach the polar regions, they disappear into snowstorms or ice storms. Otherwise, they would continue into warmer waters where they could melt away.
On average, a tropical cyclone lasts 6 hours before dissipating. However, some last for several days while others may only last an hour or less.
A normal storm moves over the ocean at around 250 miles (400 kilometers) per day, or roughly 10 to 15 miles (16 to 24 kilometers) per hour. They have been reported to travel at rates of up to 60 miles (96.5 kilometers) per hour, as was the case during the 1938 New England hurricane. However, most storms don't reach such speeds.
When a tropical storm makes landfall, it can cause extensive damage and leave many people homeless. Landslides block roads and bridges, destroying any hope of communication with outside society. Flooding spreads disease and kills livestock, and when it comes into contact with electrical power lines it can lead to long-term health problems for everyone in its path. The 2004 tsunami that devastated parts of Southeast Asia moved at more than 100 miles (160 kilometers) an hour, killing over 230,000 people in less than six hours.
Because tropical storms are defined as hurricanes that have not reached Category 5 status, they do not receive much attention from scientists or officials. But even though they aren't considered a major threat, it's important to be aware of them so that you can take measures to protect yourself and your family if one approaches. For example, if a storm is predicted, go ahead and move essential items to higher ground or into shelters.
Additionally, because tropical storms carry salt water which can enter homes through open doors and windows, residents should consider closing these openings to prevent flooding and other damage.
A tropical disturbance can become more powerful over time if it reaches a certain continuous wind speed. The three photos below show the evolution of tropical disturbances. Hurricanes may typically survive for a long time, up to two to three weeks. Less frequently, they may continue to strengthen and live up to four or five days.
Tropical depressions can remain stable for several days before dissipating. However, most depressions do not develop into organized systems and thus do not cause any damage or get noticed by the general public.
There have been cases where a depression has strengthened into a tropical storm or hurricane and then weakened again to a depression without any further warning from the weather service. In these cases, the longevity is unknown.
The life span of a tropical depression is estimated to be around eight hours. If a depression reaches 12-18 inches in sea level pressure, it can be classified as a tropical storm. If the pressure drops farther, like under major coastal mountains, then the system can become a hurricane.
Sometimes, a tropical depression will start to organize into multiple centers anemometers (wind vanes) and satellite images showing signs of rotation. These factors together indicate that the depression has begun to develop into a tropical storm or hurricane.
More heat and water will be pushed into the atmosphere. The pressure at its center will continue to fall, pulling in wind at ever-increasing speeds. The storm will build over several hours to days, eventually attaining hurricane classification when the winds that whirl around it reach sustained speeds of 74 miles per hour or higher.
The average lifetime of a tropical cyclone is about 10 days. However, some last longer than that or less than that. A few last all the way up to 20 or 30 days.
Here are some rough estimates on how long it takes for different types of hurricanes to develop and intensify:
Category 1: Less than 72 hours
Category 2: From 72 to 96 hours
Category 3: From 96 to 120 hours
Category 4/5: Over 120 hours
It should be noted that these are only averages and it can take a lot longer or much shorter than that. For example, Hurricane Harvey took almost six days to reach category 4 strength despite being nearly stationary over the Gulf of Mexico during its early stages.
Also, the energy needed to keep a hurricane going comes mostly from its surrounding oceanic surface waters. So if those waters are not there or not enough of them, then the hurricane will weaken over time.