Wind Speed Vs. Air Pressure | Sciencing
The pressure gradient is the change in barometric pressure over a distance. Big changes within shorter distances equals high wind speeds. This band of surface convergence, forced rising air, and clouds is easily seen on . Relationship between surface pressure and wind speed for a number of. Wind speed and air pressure, also called barometric pressure, are closely related . Wind is created by air flowing from areas of higher pressure.
With nearly days of hourly readings, we have a sample of size There variables included in this second data set include pressure and wind speed in addition to temperatures atmospheric, water and dew point from which we will use Wooten's augmented matrix to determine the relationship that exist among the variables including interaction between the wind speed and pressure.
Then using standard statistical methods for multiple regression, we have the following data matrices: The parameter estimates are given in Table 1 including the analysis of variance and regression statistics. This model indicates that when there is no wind present, the atmospheric pressure is approximately With a standard error of 9. As proof on concept, we will estimate this same relationship using Wooten's augmented matrix and compare the results. The alternative model is: Modeling done using standard multiple-regression can also be done using augmented matrices.
This gives a scaled model in terms of pressure as a function of wind speed of as shown in Fig. The apparent differences are due to the fact that the data used to calibrate both models where recorded under hurricane conditions and therefore standard atmospheric pressure is extrapolated information. First we will test the relationship between wind speed and pressure assuming interaction and then with the full second order model.
Consider the augmented model including interaction without second order terms: Using the developed non-response analysis, we have to be: This gives a scaled model in terms of the smallest coefficient of Where the parameter estimates are given in Table 3.
The parameter estimates are given in Table 3 ; with Solving for pressure we have: As indicated in Fig.
Wind & Air Pressure
However, there is a smaller standard error, this is an indication of higher order terms in at least one of the principle factors to explain the curvature seen in the residuals Fig. Full second order model: Consider the augmented model: Scatter plot of pressure versus wind speed including developed model including interaction Using this non-response analysis, we have to be: Residual plot of a pressure and b wind speed Solving for pressure we have: The apparent reason for the two solutions is that pressures relationship to wind speed is indirectly related by temperature and volume and therefore, the pressure would be different before, during and after a storm.
Scatter plot of pressure versus wind speed including developed model including higher order terms and interaction This is seen in the estimates when we let: This is an indication that there are lurking variables, either volume not measured or temperatures not provided in this data set are related to pressure and wind speed. This breakdown is consistent with the Wooten and Tsokos b scale, that around 80 knots there is a shift in pressure differentials and the start of hurricane category 2 in this newly defined scale.
Scatter plot of pressure versus wind speed a before the storm and b after the storm Table 4: Standard scores for wind speedpressure, temperatures atmospheric, water and dew point for a the original data and b for the day moving average In the Saffir-Simpson scale, this shift occurs at 85 knots. As these values vary from hour to hour and have daily and yearly patterns, Fig.
To compare these measures near the surface to those measured within a hurricane; consider the non-response model given in Eq.
Using this non-response analysis and the raw data, we have to be: Solving for pressure in terms of wind speedwe have Hence, solving for pressure as it has been done in the previous analysis, Eq. However, as the wind speed increase, this estimate has increase variance.
Figure 8 indicates that there is more to the relationship between pressure and wind speed near the surface of the water in the Gulf of Mexico.
This is seen in that the estimates for pressure are only accurate during the summer months when temperatures are higher.
Windy Weather II: The Correlation Between Barometric Pressure and Wind Velocity
However, in the winter months, the developed model does not accurate estimate the observed pressure. This is due to the affects of temperature. By the ideal gas law, pressure and volume are directly related to temperature, but under the assumption that pressure is constant, by Charles Law Pidwirny,here the ratio of volume to temperature is constant. Therefore, during the summer months when pressures appear to be constant, temperature should explain the interaction between pressure and volumes.
To compare the behavior of each of the various temperatures and related volumes by scaling the data as follows: Among the variables given, pressure appears to be most constant; in addition, the behaviors of the three temperature readings are very similar.
This is seen in Fig. When compared to the other variables, temperature appears to relate inversely; when temperatures rise, pressure and wind speed compensate for the moving volumes of air.
This measure is also an indication of the constant nature of the variable itself. Consider the sums of square error for the variable P: Hence, internal to the variable, the coefficient of determination is the percent of total sums of squares explained by the mean and is given by: As and therefore P is approximately a constant and as and therefore P is extremely variant.
Table 5 gives the analysis of the constant nature of the variable pressure. The estimate of the mean reciprocal is 0. Although the majority of tropical waves die out before becoming major systems, if conditons are favorable, tropical waves can intensify, develop a central low pressure region around which the winds rotate, and grow into hurricanes.
In fact, most severe hurricanes that affect the United States begin as easterly waves, which move of the continent of Africa. More information and a diagram can be found in this African Easterly Wave Link. Usually these easterly waves are relatively weak until they move into the warmer waters in the western Atlantic, Caribbean, and Gulf of Mexico.
Although most of the severe hurricanes that affect the United States begin as easterly waves that move off Africa and across the Atlantic, there have been many cases where hurricanes initially formed much closer to the United States -- in the Carribean and Gulf of Mexico. In those cases it often appears that a region of surface convergence or upper-level divergence with an associated area of disorganized thunderstorms eventually develops rotation and strengthens.
Types of Tropical Cyclones Tropical cyclone is the generic name given to a surface low pressure system over tropical waters, with organized convection i. As a tropical cyclone intensifies, it is classified according to wind speed. These storms are given different names in other ocean basins: Typhoon is used in the north Pacific Ocean west of the dateline Severe Tropical Cyclone is used in the southwest Pacific Ocean west of the dateline and in the Southeastern Indian Ocean Severe Cyclonic Storm is used in the north Indian Ocean Tropical storms and hurricanes are the only natural disasters which have their own names e.
Names seem appropriate because we commonly come to know hurricanes long before they strike land, often watching these storms move across the oceans for days or even weeks. By contrast isolated severe thunderstorms and tornadoes develop suddenly and last only hours. Hurricanes are much larger than an individual severe thunderstorm cell and are more correctly described as being composed of an organized clustering of thunderstorms.
They are quite powerful and release great amounts of energy mostly in the form of latent heat during condensation. In fact the energy released by a single, strong hurricane can be greater than the total annual energy consumption of the United States and Canada combined.
Below is a photo of Hurricane Elena. The storm is approximately km mi in diameter, which is about average for hurricanes.Chapter 5 Air Pressure and Winds
The area of broken clouds in the center is its eye. Elena's eye is almost 40 km 25 mi wide. Within the eye, winds are light and clouds are mostly broken. The surface pressure is very low, nearly mb.
Hurricane Elena as photographed from the space shuttle Discovery during September, Structure of a Hurricane Notice that the clouds align themselves into spiraling bands called spiral rain bands that swirl in toward the storm's center, where they wrap themselves around the eye.
Surface winds increase in speed as they blow counterclockwise and inward toward this center. Adjacent to the eye is the eye wall, a ring of intense thunderstorms that whirl around the storm's center and extend upward to almost 15 km 49, ft above sea level. Notice that the cloud tops in the eye wall region extend above the other clouds. Within the eye wall we find the heaviest precipitation and the strongest winds.
Figure K shows a top-down view of a typical hurricane. All strong tropical cyclones consist of the following components: All tropical cyclones rotate around an area of low atmospheric pressure near the Earth's surface. The pressures recorded at the centers of tropical cyclones are among the lowest that occur on Earth's surface at sea level.
Tropical cyclones are characterized and driven by the release of large amounts of latent heat of condensation as moist air is carried upwards and its water vapor condenses.
This heat is distributed vertically, around the center of the storm. Thus, at any given altitude except close to the surface where water temperature dictates air temperature the environment inside the cyclone is warmer than its outer surroundings.
A strong tropical cyclone will harbor an area of sinking air at the center of circulation. Weather in the eye is normally calm and free of clouds however, the sea may be extremely violent. The eye is normally circular in shape, and may range in size from 8 km to km 5 miles to miles in diameter.