How do hurricanes form?

1/3/2017 (Permalink)

Hurricanes begin when areas of low atmospheric pressure move off Africa and into the Atlantic, where they grow and intensify in the moisture-laden air above the warm tropical ocean. Air moves toward these atmospheric lows from all directions and curves to the right under the influence of the Coriolis effect, thereby initiating rotation in the converging windfields. When these hot, moist air masses meet, they rise up into the atmosphere above the low pressure area, potentially establishing a self-reinforcing feedback system that produces weather systems known to meteorologists as tropical disturbances, tropical depressions, tropical storms, and hurricanes.

Fortunately, fewer than 10 percent of disturbances grow into hurricanes. Development of a full-fledged hurricane requires a rare combination of atmospheric events. First, the tropical disturbance must produce converging air masses. Second, the converging air must rise — but not in an area where there are either strong winds or descending air masses aloft. Hurricane development requires both an organized pattern of convection that is destroyed by upper atmosphere winds, as well as unstable air masses in the upper atmosphere that can carry rising surface air away from the upper end of the developing storm.

If these three phenomena occur together, a self-sustaining circulation develops in which moist surface air rises and its moisture condenses, releasing latent heat that warms the upper atmosphere. The heated atmosphere creates lift that extends the low pressure area upward and further reduces its already low pressure. As winds in the upper atmosphere carry moist air away from this growing cylinder of low pressure, dry warm air from above can enter the center of the cylinder, ultimately reaching the sea surface and forming the cloud-free area known as the eye of the hurricane.

A system of this type will continue to intensify as long as the upper-level outflow of air exceeds low-level inflow. The relationship between inflow and outflow is controlled by the heat content of the ocean water and the latent heat contained in the moisture in the rising air. In other words, once formed, hurricane circulation will continue as long as the storm is over warm water, has access to moist air, and doesn’t drift into areas where upper-level winds can tear it apart.

Florida Forest Service Sets National Prescribed Fire Record

1/3/2017 (Permalink)

The Florida Forest Service has announced that more than 246,000 acres of Florida state forests were treated with prescribed fire last year, the highest number ever reported by any state forestry agency in the country. The Florida Forest Service administers the top prescribed fire program in the nation. Prescribed fire is a safe way to apply a natural process, ensure ecosystem health and reduce wildfire risk.

"Fortunately, there were many days last year that exhibited conditions favorable for prescribed fire. Conditions can change quickly and drastically in Florida, so the Florida Forest Service has made it a priority to take advantage of favorable conditions whenever they are present,” said Jim Karels, Florida State Forester and NASF President.

Prescribed fire is an important land management tool used to protect Florida’s homes, structures and valuable natural resources by reducing the buildup of flammable plant materials. The reduction of this hazardous buildup results in increased wildfire safety for surrounding areas. In addition, many of Florida’s plant and animal communities, such as its deer and quail populations, are dependent on the regular occurrence of fire for a healthy existence. Prescribed fires mimic this natural process, returning nutrients to the soil, providing better forage for wildlife and livestock, and helping control certain plant and tree diseases. Prescribed fires also help preserve rare and endangered plant and animal species including as the Yellow Fringeless Orchid found on the Blackwater River State Forest.

Because of prescribed fire’s important role in Florida’s ecosystems, the Florida Forest Service works hand-in-hand with private landowners and partnering agencies to promote the use of prescribed fire throughout Florida. In addition to its record breaking state forest prescribed fire program, the Florida Forest Service boasts the most active overall statewide prescribed burning program in the nation.

As the managing agency for all outdoor burning within the state of Florida, the Florida Forest Service provides a unique program that trains and verifies individuals as Certified Prescribed Burn Managers. This program helps to promote and increase the use of prescribed fire on private forest lands in Florida. Anyone who uses prescribed fire or conducts controlled burns on a regular basis should consider enrolling in this useful and educational program.

Certified Prescribed Burn Managers receive certain extra privileges such as liability protections, additional burn time and permission to obtain nighttime burning authorizations (when favorable conditions are present). Certified Prescribed Burn Managers also have the advantage of being able to submit open burn authorization requests online. Further information and application forms can be found at www.FloridaForestService.com or by contacting the Withlacoochee Training Center at (352) 797-4172.

The Florida Forest Service manages more than one million acres of public forestland while protecting 26 million acres of homes, forestland and natural resources from the devastating effects of wildfire. To learn more about Florida Forest Service programs, visit www.FloridaForestService.com.

- See more at: http://www.stateforesters.org/news-events/blog/florida-forest-service-sets-national-prescribed-fire-record#sthash.TutqbDGs.dpuf