Every year we are faced with the inevitable hurricane season. Weather warnings of storms, high-speed winds, tornadoes, flooding, and even the occasional evacuation have become an accepted part of our lives. But, how familiar are we with the actual science behind it? What exactly causes these hurricanes which we have begrudgingly learned to live with each hurricane season? Here is a general run-down of what exactly is the cause of these pesky storms.
Warm Air and Warm Water
Technically, hurricanes only originate in the Atlantic ocean or eastern Pacific ocean. The same exact storms are also known as typhoons or cyclones when they begin in other areas of the globe. No matter where they form, however, they all begin the same way.
The two essential ingredients in every hurricane are warm water and moist, humid air. This is why hurricanes begin in the tropics, or over warm ocean water near to the equator. In this situation, the humid air rises upward, leaving less air near the surface of the ocean. This creates an area of lower air pressure. Air from surrounding areas with higher air pressure pushes into the low pressure area, then that “new” air becomes warm and moist and rises, too. As the warm air continues to rise and leave the surface area with less air, the surrounding air continues to swirl in to take its place. The warmed, moist air rises and cools off, and as a result the water in the air forms clouds. The whole system of clouds and wind spins and grows, fed by the ocean’s heat and water evaporating from the surface. During certain times of the year there is more heat in these storm-prone areas, which can lead to what we know as “hurricane season.”
These weather ingredients don’t always add up to what we know as a hurricane, however. Wind speed plays a part in how destructive this weather anomaly can be. If wind speeds are less than 38 mph, this instance is known as a “tropical depression.” If wind speeds are anywhere from 39-73 mph, this is known as a “tropical storm.” Only when wind speeds exceed 73 mph do they pick up enough momentum to be deemed a true “hurricane.”
Many Atlantic hurricanes start to take shape when thunderstorms along the west coast of Africa drift out over warm ocean waters that are at least 80 degrees Fahrenheit, where they encounter converging winds from around the equator. Sometimes other hurricanes originate from unstable air pockets popping out around the Gulf of Mexico.
After the Hurricane Has Formed
As a hurricane forms, it grows and gains momentum, spinning and strengthening over the ocean. It is interesting to note that storms forming north of the equator spin counterclockwise, while storms formed south of the equator spin clockwise. This occurs due to Earth’s rotation on its axis.
As the storm system rotates faster and faster, an “eye” forms in the center of the hurricane. One might think the center of the storm would be the most turbulent, but it is actually very calm and clear within the eye, with very low air pressure. Higher pressure air from above flows down into the eye.
Hurricanes are steered by global winds. These winds, called trade winds, blow from east to west in the tropics. As a result, they carry hurricanes and other tropical storms from east to west. In the Atlantic, storms are carried by the trade winds from the coast of Africa where they typically form westward to the Caribbean and North American coasts. When the trade winds are strong it is easier to predict where the storm will travel. When they are weak it’s more difficult.
High pressure systems can also affect the path of storms. In the Atlantic Ocean, the Bermuda High affects the path of hurricanes. When the storms are carried west by the trade winds, they are pushed north around the edge of the high pressure area.
Although these factors add up to a typical hurricane path that travels west and then bends pole-ward, there are other factors that affect a hurricane’s path and complex hurricane tracks are common too.
During hurricane season, it is important to watch the news, weather channels, websites or other phone applications to be kept up-to-speed with an impending storm’s ever-changing movements.
When the Hurricane Makes Landfall
A hurricane is classified as making landfall when the center of the storm moves across the coast; in a relatively strong tropical cyclone, this is when the eye moves over land.
Tropical cyclones, or hurricanes, usually weaken when they hit land, because they are no longer being “fed” by the energy from the warm ocean waters. However, they often move far inland, dumping many inches of rain and causing much wind damage before they die out completely.
It should be noted that the affects of the storm are felt long before the official “landfall,” as the outer bands of the storm start their destruction before the eye actually reaches land. Flooding rains and even tornadoes can strike just within the outer bands. It is even possible for these outer bands to strike and cause chaos over land, and then the hurricane can move back to sea, without the eye ever crossing into a continent.
Once a hurricane makes landfall, it is separated from its ocean energy source, and hence, can no longer extract heat from the ocean. Since the air masses over land are drier and contain more aerosol particles than over the ocean, less moisture is carried into the storm, cloud coverage lessens, and air is cooled and then sinks, disrupting the hurricane’s secondary circulation and hindering critical thunderstorm development. To a lesser extent, the increased roughness of the land surface also weakens a hurricane as increased friction causes a reduction in surface circulation.
Preparing for the Storm
As hurricanes are an act of nature, and therefore unpredictable to an extent, it is important to be prepared for these storms long before they actually strike, and especially before hurricane season hits. This is why it is important to protect your home or business with a reputable hurricane protection company such as Armor Screen. Call us today at 877-237-2337, or fill out our online form to find out more about what custom solution Armor Screen can provide for you. Don’t go unprotected this hurricane season!
