Atlantic Hurricanes

Bermuda High

The Bermuda High pressure system stays over the Atlantic Ocean during the summer time. The Bermuda High acts as a block that hurricanes can't penetrate, its size and locations determine where hurricanes go. If the Bermuda High is what we would say "normal," it usually leads hurricanes to move up the East coast. Because hurricanes can't penatrate through the Bermuda High, the hurricane will go around the Bermuda High. The Bermuda High goes in a clockwise circulation around the high pressure brings hot and humid wind to the Southeast and East. In the summer, the main storm track shifts so it goes to the North, so storms generally are to weak to drag cool air to the Southeast, so it usually leads to hot and humid weather to the Southeast. The ocean water that are cooler than land cause the Bermuda High to remain its strong formation during the summer.

Water Temperature

When a hurricane passes over an ocean, the powerful winds stir and mix the warm surface water with the colder deeper water. Because of the mixing results caused by the hurricane, the warm water is being forced down into the deep ocean, and the cold water being brought up to the surface layer of the ocean. It is suggested that the heat pumped into the ocean by hurricanes strengthens storms that pass in that general same area because ocean heat is the energy source that powers hurricanes. Most of the heat from the warm water that hurricanes mix deep into the ocean is returned to the atmosphere in the the winter if the hurricane happened during the summer or fall. Scientists have looked at the satellite data they collect from the increase of major storms, and from that they say with the more intense storms the sea surface temperatures are rising and hurricanes live off of the warm sea water. A hurricane builds its energy from warm ocean water , and as water heats up, the water turns into water vapor. And as the water vapor rises, it cools causing the vapor to turn into rain and releasing more heat to fuel the hurricane.

El Nino

El Nino is an abnormal warming of surface ocean waters in the Eastern tropical Pacific. El Nino is a part of what is called the "Southern Oscillation." Because of ocean warming and pressure reverals are mainly simultaneous that scientists call the ENSO, (El Nino/ Southern Oscillation) fishermen from South America gave it the name "El Nino" which means "The Christ child" in Spanish because it comes around Christmas time. Scientists believe that El Nino might have contributed in the 1993 Mississippi and 1995 California floods along with drought conditions in South America, Africa, and Australia. In the 1500's, a fisherman wondered about a current of unusually warm water that came to their shore every couple years around Christmas time. They named the hot water "El Nino." The hot water usually comes first to the coasts of Peru and Ecuador in South America. El Nino is characterized usually by warm ocean temperatures in the Equatorial Pacific. El Nino is an oscillation of the ocean-atmosphere system in the tropical Pacific causing important consequences for the weather around the world. Some of the consequences that occur are increased rainfall which causes flooding on the South and a drought in the West Pacific. If normal conditions occur with El Nino, the trade winds blow towards the West going across the Pacific. While El Nino is happening, the trade winds relax in the Central and Western Pacific leading to a depression of the thermocline in the Eastern Pacific and an elevatioin of the thermocline in the West. The result of a reduced efficiency of upwelling to cool the surface and cut off the supply of nutrient rich thermocline water to the euphotic zone will have the effect of a rise in the sea surface temperature and a huge decline in primary productivity. You can see El Nino in the sea surface temperature in the Equatorial Pacific Ocean. El Nino can be seen in measurements of the sea temperature. When an El Nino occurs, it is usually very srtong. A strong El Nino is shown by the warm water spreading from the Western Pacific to the Eastern Pacific.

La Nina

La Nina means "Little girl" in Spanish. La Nina is occasionally called "El Viejo, anti-El Nino," or even sometimes "Cold event" or "Cold episode." La Nina is usually characterized by cold ocean temperatures in the Equatorial Pacific, so the opposite El Nino. El Nino and La Nina alternate to about every 3 to 7 years. The strengths of these two events are judged by the pressure anomaly which varies from case to case. La Nina is a ENSO cold event can be used to describe those times of cold in Eastern and Central equatorial Pacific SST anomalies.