Hurricanes are the most powerful weather phenomenon there is on earth. It can contain within it, enough energy to light New York City for 10 years!! The hurricane can have winds sustained at over 200 MPH and gut to about 250. Meteorologists are not sure because no wind measuring instrument has been able to measure the winds, as the winds are too strong. The hurricane is created over the seas and it is the shoreline that takes the brunt of the force with the storm surge, which I will discuss later. And it is the hurricane that can be the most devastating force on earth--except--they are so big, that we can see them as they form from a THUNDERSTORM to a tropical depression, to a tropical storm and then a hurricane (the types of tropical weather will also be discussed later). Lets begin where a hurricane does, as a thunderstorm.

As I have discussed in my other page about  THUNDERSTORMS, a hurricane is born out of a mature thunderstorm. This thunderstorm grows from one thunderstorm to many and they become organized over warm oceans, usually >80 deg. Fahrenheit. Here, the storms have plenty of "fuel" to feed from as the ocean is virtually an endless supply for the storm. As the storm grows, it creates winds and updrafts as in a thunderstorm, but on a larger level. As these winds increase, it brings more energy into the storm in the form of more moisture. From there, the storm winds increase and the storm is now tropical in nature.

A thunderstorm now becomes a tropical depression as the winds have increased up to 38 MPH. The barometric pressure drops and the low pressure creates a spin in the whole storm. If the weather conditions are right-and upper level high pressure, no upper level winds to sheer the clouds apart, and warm enough water, the storm will continue to grow. As it does, its organization--or its ability to spin somewhat regular in shape--is better and the winds increase more. As the winds approach 38 MPH, the storm now becomes a Tropical Storm.

A tropical storm is an increased level of the storm, only now the winds are greater and the pressure is much lower. If the conditions still favor growth, this is when a simple thunderstorm now has grown to hurricane strength. It officially becomes a hurricane when the winds reach 74 MPH and the eye of the storm now becomes visible. At hurricane strength, the winds are able to begin pushing the oceans water ahead of it--called the storm surge.

If the winds are still consistent, the favorable conditions are still prevalent, and the upper level of the atmosphere cooperates, the hurricane begins to go through "levels" or categories of hurricanes. each category represents higher speed winds and lower barometric pressure. Lower barometric pressure is in indication of strengthening of the storm. For instance, if a hurricane's winds were from 74 MPH to 95 MPH (64-83 knots) the classification is a category 1 hurricane. What is the classification, you ask? It's called the SAFFIR-SIMPSON SCALE which is located on the WEATHER CHANNEL's  home page. The link gives you a great graph of the scale and a great description of what each category is capable of, destruction-wise.

Below is a picture of what a category 5 hurricane looks like from a satellite's point of view. Notice how large the hurricane is as a whole and note the opening in the middle of the storm. I'll explain that phenomenon below.

I found this picture at  http://rsd.gsfc.nasa.gov/ which has another great area to see more images of hurricanes.

The opening in the center of the hurricane is what is known as the eye of the storm. In here is an eerie calm with light winds, no rain and the sun pops out if the sun is high enough in the sky. Many people have falsely believed that this is the end of the storm. It isn't, as a matter of fact, the worst is yet to come in some cases. Surrounding the eye's serene atmosphere is the eye wall which packs the highest winds in the hurricane. This is where the hurricane's energy is the most tightly packed similar to a whirlpool. Within the eyeball, TORNADOES can be formed, and also where the storm surge is highest on the north-eastern section of the storm. The reason that I say the worst is yet to come is because when the eye passes, the eyeball will have gone over you once with winds rushing from the northeast, then as it has passed you, the winds reverse themselves and blow just as hard from the other direction. Anything that had been loosened up from the first half of the storm will more than likely blown over and destroyed.

I've mentioned the storm surge. What is this exactly? We hear of it all the time when it comes to hurricanes and this is the most dangerous part of the storm, over the winds and the rain. It is the buildup of ocean water that has been pushed ahead of the storm by its winds. The worst part of the storm surge depends on where you live. If you live on the east coast of the U.S. then the north side of the hurricane will get the worst of the storm surge. On the west coast of Mexico and Central America, the southern section of the storm has the worst. The reason behind the different locations (northern to southern) is due to the cyclonic rotation of the storm, or simply, the direction of the spin. The spin is always counter-clockwise in the northern hemisphere (the section of the earth above the equator) because of what is known as the Coriolis Effect. This phenomenon is the same reason that your toilette flushes counter-clockwise. It has to do with the rotation of the earth.

CORIOLIS EFFECT
                        A force per unit mass that arises solely from the earth's rotation, acting
                        as a deflecting force. It is dependent on the latitude and the speed of
                        the moving object. In the Northern Hemisphere, air is deflected to the
                        right of its path, while in the Southern Hemisphere, air is deflected to
                        the left of its path. It is greatest at the poles, North and South, and
                        almost nonexistent at the equator.

Hurricane Hugo, 1989, the hurricane took a path that went from the African coast, where a lot of Atlantic hurricanes are born, over Puerto Rico and up the coast until it decided to hit just north of Charleston, devastating the coastline. Another facet of the hurricane is that it can strengthen and weaken as it pleases. Hugo was predicted to come ashore (once they knew where) as a category 3. It ended up coming ashore as a category 5! As predictable as they are, they are just as unpredictable, but with each passing year, the technology and knowledge of these great storms is getting better. Soon, we can predict well ahead of the hurricane, where it will hit, and how long. We will never have a way to stop it though, and it is up to you to be prepared.

E. Tallberg                                    ||main||meteorology main page||cosmology||personal||mark||links||
tinytall@oocities.com
Dec. 1997                                                Back to Tornadoes      Back to Thunderstorms