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# Windy Weather II: The Correlation Between Barometric Pressure and Wind Velocity (page 2)

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### Hypothesis

I hypothesize that as the barometric pressure increases the wind velocity will decrease. This is based on my background information, which states that in a low pressure zone air rise and rotates faster in the high atmosphere forming high winds. In high pressure zones the air sinks and doesn’t rotate as fast as the rising low pressure air in the higher atmosphere, forming low speed winds.

### Materials

1. Anemometer
2. Formula to convert rotations per minute into miles per hour
4. Data log
5. Stop watch/clock

### Procedure

Independent variable – barometric pressure Dependent variable - wind velocity

1. First, I recorded the date, time, and barometer readings that I got off the Internet web site, Weather.com in my data log.
2. Next, I took the wind velocity by timing myself for one minute, and then I counted on my anemometer the rotations per minute. I measured the wind speed from the same location everyday holding the anemometer above my head.
3. I performed this procedure from October 27, 2003 until December 1, 2003. I recorded my findings at the times of 6:30 am, 11:30 am, 6:00 pm, and 9:30 pm.
4. I converted the wind velocity from rotations per minute to miles per hour. (See instructions for 05-005 anemometer)

### Discussion

The data tells us that there is a negative correlation between barometric pressure and wind velocity. On my scatter plot the highest wind velocities show this by decreasing as the barometric pressure increases. I had a correlation of - .447172. This tells me that there is a relationship between barometric pressure and wind velocity but not a perfect negative correlation of -1.

### Conclusion

By conducting this science experiment I wanted to find the correlation between barometric pressure and wind velocity. I hypothesized that as the barometric pressure rose the wind velocity would fall. I chose this hypothesis because my background information stated in low pressure zones air rise and rotates faster than high pressure sinking air, forming fast wind currents. Each day I took the barometric pressure and wind velocity at 6:30 am, 11:30 am, 6:00 pm, and 9:30 pm and recorded them in my data log. I started collecting my data October 27, 2003 and ended December 1, 2003. When I completed my data collection I converted my wind velocity from measurements of rotations per minute to miles per hour and then compared the wind velocity and barometric pressure on a scatter-plot. I found that my hypothesis was correct that as barometric pressure increase wind velocity decreases. The correlation was -0. 447172.

The wind velocity decreased as the barometric pressure increased on my scatter-plot. This answered the problem because the relationship the correlation between barometric pressure and wind velocity is that as the pressure rises the wind velocity falls. This was the same as what my background information stated. My background information stated that wind velocity rises as barometric pressure falls. This is caused by rising air currents in the center of a low pressure system. Since the upper atmosphere currents move faster than the low atmosphere, the rising air currents in the low pressure system move faster than the sinking air currents in a high pressure system. This causes winds speeds in low pressure systems to be faster than in high pressure systems. I found this information on the web-page http://www.personal.psu.edu/faculty/j/e/jea4/earth/windsystem.html. The data supports that barometric pressure and wind velocities are related. On my graph the highest of the wind speeds showed a negative correlation between barometric pressure and wind velocity because as the wind velocities decreased the barometric pressure increased. The wind speeds varied from 0 to 45 miles per hour with many outliers and the barometric pressure varied from 29.4 to30.8 inches with many outliers. My highest wind velocities give support that as the barometric pressure increases the wind velocities fall in an almost straight diagonal line on my scatter plot. This shows a negative correlation.

My conclusion is very accurate because I have a great amount of data. I had much more than I needed to find the relationship between barometric pressure and wind velocity. I think I could have taken more data and still have had the same relationship between the two variables. Knowing that high winds come with lower pressure systems is important because you can predict if a storm is coming. For one more example, tornadoes occur in low pressure zones. It is important to know that high winds come with low pressures because you can prepare for the consequences, you can take down your umbrella, go sailing, or if you are in an area usually threatened by tornadoes you know to be extra cautious because of the low pressure. The correlation between barometric pressure and wind velocity is that as pressure increase wind velocity decreases.

### Applications

• Use pressure gradient differences to predict possible high winds
• Help us prepare for severe weather events
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