Michael P 10/9/2000
Ms. Freese Hurricane Report
A Recent Study of Hurricane Dennis:
I. Introduction:
A thick sheet of Darkness covers the sky. Heavy downpours drench all that is beneath them. Powerful winds whistle and howl uncontrollably, rustling against trees and houses. During a hurricane, all of this can be expected. To most people, a spiral-like shape can best identify these massive storms. In Galveston, Texas over one hundred years ago, a hurricane hit the area with awesome force. It caused houses to be ripped apart, trees to be blown down, and people to be swept away by the rushing water. This demonstrates the unbelievable power of hurricanes and shows that they ought to be perceived with extreme caution.
In early times, a hurricane could hit any given location with little or no warning due to the lack of technology. The most warning one could receive was the signal of a flag, which if was far away would not be seen. Since most people were unprepared when the storm was coming, this caused major damage on the land that the storm passed over. For this reason. alone, predicting hurricanes is worthwhile for it can help to save lives and property.
II. Procedure:
Twenty-four storm advisories, satellite photos, and a tracking map were used to study the behavior of the Hurricane Dennis. The advisories gave the date, wind speed, location, air pressure, and time of the storm. On the tracking map the path of the storm would be plotted using the different advisories. This would show the distance the storm traveled in a given amount of time. With this data, the storm speed could be calculated. Along with the storm speed of the storm, the approximate size of the storm was determined so that the states/areas it would affect would be known.
III. Conclusions:
Hurricanes can be predicted by examining certain factors regarding the storm, such as the speed of the storm, the relationship between wind speed and air pressure, what effects the storm, and the area it would span. With this data people can be effectively warned about what the storm is going to do next. After all preparedness is a key to survival during a hurricane.
One of these storm factors was the degree of relationship between the wind speed and air pressure of Hurricane Dennis. After a study involving the two variables, it was shown that there is a high negative correlation, or relationship, between the wind speed and the air pressure. R, the correlation coefficient, was equal to 0.96 on the negative side of the correlation scale (from –1 to1). If there were a perfect correlation, the line would be equal to negative one. When one variable (wind speed) increased, the other variable (air pressure) decreased. For example, on the 7th advisory when the wind speed increased from 45 miles per hour to 65 miles per hour, the pressure decreased from 1004 millibars to 1000 millibars. This would mean that the scattergram of wind speed and pressure would have a negative rate of change, or slope. After r was squared (which is the shared variance) it was found that wind speed accounts for 91.4 % (r squared = 0.914)of the variance or change in air pressure. It cannot be said that wind speed always attributes to the air pressure. Although it can be concluded that each of the variables tend to change simultaneously. The analysis of the relationship between wind speed and pressure is necessary, because it allows one variable to be predicted if information about the other variable can be discovered.
The storm speeds of Hurricane Dennis were found by dividing the distance traveled by the amount of time it was traveled in using the tracking map. For instance, between the fourteenth and sixteenth advisories the storm traveled about 175 miles in 12 hours.
75/12 = 6.3
This meant that the storm speed was approximately 6.3 miles per hour at this point.
Throughout further analysis of storm speed, it was found that the minimum speed of the storm was 3.3 miles per hour and the maximum speed was 14.6 miles per hour. The mean speed was 8.2 miles per hour. However this cannot be the average speed used for there was much error found with this calculation (percent deviation). When the percent deviation was found for maximum speed it was 78% and for minimum speed it was 60% (calculation used was: maximum (or minimum) speed – accepted value/ accepted value x 100). This proves that mean would not be useful. When looking at all the speeds of the storm, the hurricane spent most of its time at 12.5 miles per hour, the mode. The median of all the speeds was 7.5 miles per hour. For these reasons mode and median are more substantial than mean.
Storm speed was affected most by land, as well as the wind speed. As the hurricane began to approach land it also began to slow down. The maximum storm speeds were over water and the minimum storm speeds were near land or over the islands.
For the first few storm advisories, the hurricane was traveling in a northwest pattern. It changed direction at about 20-21 degrees N Latitude. This could’ve possibly been caused by the planetary winds which blew in the same direction as Hurricane Dennis did.
After finding storm speed, several calculations and measurements helped to find the size of Hurricane Dennis. In order to acquire the size of the storm two different locations had to be measured in distance from each other from centimeter to miles, in this case being Daytona Beach, Florida to West Palm Beach, Florida. The scale on the large-scale map read 225 miles for every 2.25centimeters. For the two locations the distance was 16 centimeters:
4.5 cm = 16 cm
50 m x
800 m = 4.5x
4.5 cm 4.5
177 miles = x
On the satellite photo the distance between the two locations was 1.7 centimeters. The diameter of the storm of the satellite photo was about 3.8 centimeters. Then the diameter was measured in miles:
1.7cm = 3.8cm
177 m x
672.6m = 1.7x
1.7cm 1.7
395.6 miles = x
In order to find the area, pi had to be multiplied by the radius (197.8) squared:
3.14 x (197.8 x 197.8)
3.14 x 39124.8
The approximate area of Hurricane Dennis was about 122,852 square miles. It had the capability of covering the entire state of Florida and most other states in the USA. However some states did have the storm beat in size such as Alaska, Texas, Montana, and California, which covers over 140,000 square miles each. Since the storm is so large, there is a possibility that it could occupy more than one state at a time.
Despite all the evidence found about the hurricane, possible flaws may have been involved in the experiment. Some of this error could have perhaps been caused by the missing advisories taken for the storm. Since one or two of the wind speeds and pressures of the storm were not recorded, there is a chance that the degree of correlation between these two variables is a bit off.
When putting lives and property first, predicting hurricanes is very important.. Constant warnings about the approaching storm will help to keep people informed enabling them to prepare themselves for the worst. If people evacuate the predicted path of the storm much damage can be prevented. One can successfully predict a hurricane after they are given available information such as storm advisories letting them know one if they are at risk.
Most often predicting hurricanes is worth the time and effort. Unfortunately hurricanes are not always predicted successfully. False predictions cause many problems. People may panic for no reason and take unnecessary precautions or worse; people may feel insecure and not take the proper safety measures at all. This shows that predictions of hurricanes are not accurate all the time.
Although predicting hurricanes has its risks of being inaccurate they are, they are essential and beneficial. At least trying to predict storms is necessary for there is a good chance that the predictions are correct. Time must also be spent to update the tools used for prediction. "Its better to be safe than sorry." In most cases property and lives can be saved by predictions.