What is Wind: Definition and 858 Discussions

Wind is the natural movement of air or other gases relative to a planet's surface. Wind occurs on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few hours, to global winds resulting from the difference in absorption of solar energy between the climate zones on Earth. The two main causes of large-scale atmospheric circulation are the differential heating between the equator and the poles, and the rotation of the planet (Coriolis effect). Within the tropics and subtropics, thermal low circulations over terrain and high plateaus can drive monsoon circulations. In coastal areas the sea breeze/land breeze cycle can define local winds; in areas that have variable terrain, mountain and valley breezes can prevail.
Winds are commonly classified by their spatial scale, their speed and direction, the forces that cause them, the regions in which they occur, and their effect. Winds have various aspects: velocity (wind speed); the density of the gas involved; energy content or wind energy. The wind is also a critical means of transportation for seeds, insects, and birds, which can travel on wind currents for thousands of miles.
In meteorology, winds are often referred to according to their strength, and the direction from which the wind is blowing. Short bursts of high speed wind are termed gusts. Strong winds of intermediate duration (around one minute) are termed squalls. Long-duration winds have various names associated with their average strength, such as breeze, gale, storm, and hurricane. In outer space, solar wind is the movement of gases or charged particles from the Sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space. The strongest observed winds on a planet in the Solar System occur on Neptune and Saturn.
In human civilization, the concept of wind has been explored in mythology, influenced the events of history, expanded the range of transport and warfare, and provided a power source for mechanical work, electricity, and recreation. Wind powers the voyages of sailing ships across Earth's oceans. Hot air balloons use the wind to take short trips, and powered flight uses it to increase lift and reduce fuel consumption. Areas of wind shear caused by various weather phenomena can lead to dangerous situations for aircraft. When winds become strong, trees and human-made structures are damaged or destroyed.
Winds can shape landforms, via a variety of aeolian processes such as the formation of fertile soils, such as loess, and by erosion. Dust from large deserts can be moved great distances from its source region by the prevailing winds; winds that are accelerated by rough topography and associated with dust outbreaks have been assigned regional names in various parts of the world because of their significant effects on those regions. Wind also affects the spread of wildfires. Winds can disperse seeds from various plants, enabling the survival and dispersal of those plant species, as well as flying insect populations. When combined with cold temperatures, the wind has a negative impact on livestock. Wind affects animals' food stores, as well as their hunting and defensive strategies.

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  1. S

    How Does Wind Affect the Doppler Effect in Jet Flight?

    Homework Statement Two jet airplanes are flying due east. The leading jet is flying at 1.3 times the speed of sound. The trailing jet is flying at 464 mph (both relative to the ground). The wind is blowing 182 mph due west. If the engine of the leading jet has a frequency of 2824 Hz, what...
  2. russ_watters

    News What do Cape Wind and Nuclear Power Have in Common?

    What do Cape Wind and nuclear power have in common? Opponents come out of the woodwork to oppose both and there is no regulatory framework in place to limit the challenges for either. As a result, opponents can litigate the projects into oblivion. Case in point, Cape Wind. It is currently...
  3. M

    Velocity potential for wind over a semi cylinder

    Homework Statement A wind flows along the horizontal ground with strength U and over a long semi cylinder. The flow can be described using two dimensional potential theory Find the velocity potential Homework Equations The Attempt at a Solution I'm not sure what to do. The...
  4. G

    Can wind turbines harness energy from moving vehicles?

    Consider a wind turbine placed alongside a road in a location with no wind. If a vehicle drives past (without loss of generality, at a constant speed) the turbine will spin and electrical power can be produced. The power produced is obviously supplied by the vehicle. As compared to the case...
  5. S

    Wind & Solar: A Renewable Energy Future?

    From the little bit I've read online it seems like wind and solar have the most potential. Also, can you get student loans if you are unemployed? (I have a good credit rating and I'm in the US)
  6. R

    Understanding Wind Power Variability in Crowsnest Pass

    The wind power that is generated using the wind mills in a wind tunnel like the crowsness pass can't be constant. How can the amount of wind be counted on because with gloabl warming maybe wind will not be as often in the future?
  7. F

    Baseball Parametric Equations with Wind

    Homework Statement A baseball is hit with an initial velocity of 103 ft/sec, with an initial height of 3 ft, and at an angle of 41 degrees. There is a wind blowing 22ft/sec in the direction opposite to the horizontal path of the ball at an angle of depression of 12 degrees. Assume that gravity...
  8. E

    Wind Turbine Design - Help w/Equations for Power Output

    Hi, I'm currently trying to design a wind turbine for a college project. I know the ideal equation for power is (mass x area x velocity cubed)divided by 2. Is there anyone who could help with equations relating the power output to the number of blades and angle of the blades. Thanks
  9. F

    Is Over 100% Solidity Normal for Wind Turbine Blades Near the Hub?

    Hello. I'm calculating the different parameters of a turbine design but I have some trouble with the solidity. The solidity near the hub exceeds 100%, but is an average of ~27% for a 6 bladed turbine. I'm just wondering if anyone has had experience in turbine design and if +100% solidity is...
  10. S

    Why Does Wind Feel Cool on a Hot Day?

    Hey guys I got a thought question. When air is moving, it is said that they have a higher kinetic energy than still air. Thus, the temperature of moving air should be higher than still air right? But then sometimes on a hot day why does the wind make us feel cool? I know there's hot wind but...
  11. L

    Solving the Direction of an Airplane Flying in the Wind

    Here's the problem: An airplane is flying on a bearing of 340 degrees at 325 mph. A wind is blowing with the bearing of 320 degrees at 40 mph. a) Find the component form of the velocity of the airplane. b) Find the actual ground speed and direction of plane. I can find the component form...
  12. R

    Making a Wind Tunnel for Education - Engineering Project

    Hi friends I am a mechaincal engg. student and I asked yesterday my professor of fluid mechanics that there should be a educational wind tunnel in our laboratory to understand concepts of streamlines, lift and drag better and visually. He replied me with a challenge that I should make such a...
  13. W

    Wind Turbine: 8MWatts Increase at 650ft?

    1. Wind turbine produces 8MWatts (If wind speed is proportional to the 7th root of altitude) (Wind power is proportional to the cube of wind speed First the turbine is at 450ft then reconstructed at 650ft, how much faster is wind speed? and how much more power?2. Sw= 7√Altitude, Pw= (Sw)33...
  14. C

    Math Fundamentals: My 2nd Wind in Middle School

    Up until middle school.. math was my thing. I wouldn't say I "enjoyed" it, but it definitely came naturally. My teacher even forced me to do math counts in 7th and 8th grade. We had a grad student as our coach and he always tried to get me into math, and, for whatever reason, I just really...
  15. C

    Wind resistance on an airsoft BB

    Hey, I have a question pertaining to the effect of wind resistance on a 0.2 gram plastic, spherical airsoft bb over a given distance. I know it has something to do with drag coefficient, and I’ve been having a little trouble calculating it myself, so I would really appreciate any ideas and/or...
  16. B

    How Does Wind Speed Affect Airplane Navigation?

    Homework Statement A car leaves point A and drives at 80.0 km/h [E] for 1.50h. It then heads north at 60.0 km/h for 1.00h and finally [30o W of N] at 100.0 km/h for 0.50g arriving at point B. a) Determine the displacement of point B from point A. b) A plane flies directly from point A to...
  17. H

    Design of a wind turbine kit for a car

    Hi! I’m a 4th year student at mechanical engineering. I have been asked to design a kit that can be installed in a car/vehicle which can be used to recharge the car's battery or connected to some of the car's/vehicle's component to power them. Where and how do I start? Does anyone have a...
  18. T

    Confirming Solar Wind & X-Ray Flux Effects on Earth's Magnetic Field

    This is more of a confirmation that I got the facts right: Reading around, I found out that the solar wind travels from the Sun to the Earth at a mean speed of 400km/s. Does this mean that it takes around 4 days for a burst of solar wind to cause disturbances in the Earth's magnetic field...
  19. P

    Newtonian Mechanics, accounting for wind?

    hey everyone I'm in year 12 physics, and we have a project revolving around the physics of sport i selected golfing, and my initial aim is to investigate the inaccuracy associated with predicting the aerodynamic motion of a golf ball (max height, max distance). i selected this mainly...
  20. S

    Find Initial Velocity (With Wind Factored In)

    [Please Help!] Find Initial Velocity (With Wind Factored In) I can't do it =\. Q: What equation would I use to find initial velocity? Given: Wind Speed, Wind Angle, Coordinates of Origin, Coordinates of End Point, (Distance), Projectile Mass, Theta (Angle to Use) Here's my repost from a...
  21. B

    Calculating Displacement & Airspeed with Wind Speed

    wind speed? Homework Statement A car leaves point A and drives at 80.0km/h [E] for 1.50h. It then heads north at 60.0 km/h for 1.00 h and finally [30o W of N] at 100.0 km/h for 0.50 h, arriving at point B. a) Determine the displacement of point B from point A. b) A plane flies directly from...
  22. J

    Velocity of a boat after feeling the wind force

    Homework Statement A boat is 400 kg and cruising along with a constant speed of 4.0 m/s in a direction 30 degrees north of east. The boat suddenly begins to feel a force from the wind that is 45 degrees north of east and has a magnitude of 100N. After a 10 second period what is the velocity...
  23. M

    Navigating Wind: Flying East in a Light Airplane

    Homework Statement You are flying in a light airplane spotting traffic for a radio station. Your flight carries you due east above a highway. Landmarks below tell you that your speed is 52.0 m/s relative to the ground and your air speed indicator also reads 52.0 m/s. However, the nose of your...
  24. rootX

    News Feasibility of Wind and Solar Power in Ontario

    http://greeninc.blogs.nytimes.com/2010/01/21/samsung-signs-66-billion-deal-to-build-wind-and-solar-power-in-ontario/?scp=1&sq=Ontario%20wind%20and%20solar&st=cse Would it be feasible?
  25. A

    Wind Tunnel Experiment(pressure problem)

    Hey everyone, first time user here! I'm doing a lab experiment with a small open wind tunnel and I'm having some trouble figuring out how to calculate the airspeed in the test section. There is a digital pressure gauge displaying what I was told to be the dynamic pressure. The pressure...
  26. H

    Finding Velocity of Airplane & Wind: An Analysis of Triangle ABCD

    Homework Statement Airplane flies over route in shape of triangle ABCD. Time(t1, t2, t3) of flying over sections AB, BC, CA are known. Lenght of sections is also known. During fly wind is present. velocity of wind is constant, and speed of airplane relative to wind is also constant. Find...
  27. L

    Can a Wind Turbine Improve Gas Mileage in Electric Cars?

    I know this question was already asked but I wanted to tackle it from a different angle. I saw allot of posts on how it would take too much gas to create the energy from the turbine but for the example let's say the car is electric. Now say we have a system where the turbine is in a...
  28. A

    Wind Tunnels: Exploring Operation Principles and Test Rhombuses

    Guys, i need some help on wind tunnels here. Basically i need to find out more on the operation principles behind wind tunnels. Basically, wind tunnels provide simulation environment of high speed (transonic) flows by mimicking the reynolds number on the actual flow, because of dynamic...
  29. H

    Calculating Effect of Wind on Sprint Time: Why?

    Hello guys, could you please help me to solve this problem? A student normally needs 15 seconds for a 100m sprint. One day favorable wind conditionshelp her to increase her speed by 2km//h. What is her time now? A) aprx. 13,8 sec. B) aprx. 13,6 sec. C) aprx. 13 sec. D) aprx. 14,2...
  30. S

    Introduction to Wind Instruments

    Homework Statement The physics of wind instruments is based on the concept of standing waves. When the player blows into the mouthpiece, the column of air inside the instrument vibrates, and standing waves are produced. Although the acoustics of wind instruments is complicated, a simple...
  31. S

    Wind Turbine Simulator experiment-formula needed

    Homework Statement I did an experiment on a wind turbine simulator I'm am doing an assignment and I need to draw up a prediction on what I think will happen I am trying to find a Formula where I can put in the input values ie 1500rpm, Excitation voltage, Hz .so that I can put in these...
  32. J

    FYP inquiries - Vertical-axis Wind Turbine

    Hi, I am a Mechanical student, currently at my final year so I am to do my FYP aka Final Year Project with the title of hybrid power generator (solar + wind). My friend is in charge of the solar part while I am to design a vertical-axis wind turbine. I am clueless about from where should I...
  33. U

    Wind speed (100mph) to Pressure (psi)

    ok guys I am an old guy that is useless at maths so i'd like your help. I have searched the net and this forum and i have found some formula but I am to thick to work it out even with an equation. https://www.physicsforums.com/showthread.php?t=117105 This isn't home work as i haven't been to...
  34. S

    Doppler Effect Wind: Frequency, Velocity, Wavelength

    Homework Statement An observer is in rest.A source of sound is in rest.A wind blows along the line joining the observer and the source.What all remain same in these: a.frequency b.velocity of sound c.wavelength Homework Equations f prime=f(v+w-vo)/(v+w-vs) Doppler effect The...
  35. P

    Build a Small Wind Turbine Using the Kidwind Motor

    we need to make a wind turbine using this motor http://www.kidwind.org/xcart/product.php?productid=15&cat=79&page=1" the rules can be found here: http://www.mrmaloney.com/nssl/events/2009-2010/0910_4-jan-wind.pdf" We were thinking, since they will be using P=(I^2)R instead of P=IV to...
  36. R

    Net force on roof from wind? Using Bernoulli's eq?

    Homework Statement If wind blows at 24 m/s over your house, what is the net force on the roof if its area is 300 m squared? Homework Equations Bernoulli's equation? P1+1/2pv1sqrd+pgy1=P2+1/2pv2sqrd+pgy2 The Attempt at a Solution Really didn't know where to go with this. I...
  37. M

    Riding against the wind- complicated bicycle problem

    Homework Statement A wind is blowing against a bicycle rider at a velocity of v0 = 10m/s. The rider is driving with the same power as in the windless weather, but he requires twice as much time to pass the straight part of the road as in the windless weather. With what velocity is he riding...
  38. X

    How Do I Calculate the Output of My Wind Turbine Using Faraday's Law?

    guys I am trying to do calculations for coils that i want to use...i don't know how to do faradays law..this is the information i have... 2inch coils, 80 turns (4layers, 20turns each layer) average diameter is .75 inches. distance from magnet is .25inches. speed is 80turns in 1.123seconds...
  39. M

    Force of Wind on a moving object.

    Hi All, I have a problem in which I am trying to calculate the force of the windspeed, x, on a surface area of a moving object, y. I am applying this to a monorail model, where a monorail carriage (lets for this purpose assume its a rectangular box) with a surface area on one side is y, is...
  40. A

    Heating water with a wind turbine

    Hello, I am new to this forum, I thought you guys could send me in the right direction. what I am trying to do is heat water with a wind turbine. the turbine produces 3 phase wild AC with voltage of 0 to 270V. related to wind speed. I am aware of the general practices with wind turbines-...
  41. M

    How Does Wind Speed Affect the Force on a Monorail Carriage?

    Hi All, I have a problem in which I am trying to calculate the force of the windspeed, x, on a surface area of a moving object, y. I am applying this to a monorail model, where a monorail carriage (lets for this purpose assume its a rectangular box) with a surface area on one side is y, is...
  42. B

    Calculating Electric Power from Wind Turbines

    Homework Statement Consider a wind turbine farm that uses turbines with a blade span diameter of 80 m at a site subjected to wind speeds over the range of 4 to 32 m/s. Taking the overall efficiency of each turbine to be 25% and the air density to be 1.112 kg/m3, determine the electric power...
  43. B

    Random variability of wind patterns

    I've been wondering lately why the air currents don't travel in the same direction. The Earth spins constantly and each side is given roughly equal irradiance from the sun, so why does the wind not simply follow this direction (on a macro scale) of heat input? Instead it seems to mix quite...
  44. V

    Designing Connector for Wind Turbine Blade Root

    Hi Guys, I have a project to hand in before xmas. Basically I have to design a connector for a Wind turbine Blade. ie the Blade root, the one that connects to the hub. for this I have to come up with original ideas, so I cannot use another current of previous blade root connector. I have to...
  45. T

    Why are Horizontal Axis Wind Turbines used other than Vertical Axis?

    Why are Horizontal Axis Wind Turbines used more often than vertical axis when it looks like a vertical axis has more of an advantage? Please can you explain it simply?
  46. M

    Calculating Wind and Quadratic Drag on a Golf Ball in Flight

    Homework Statement This is a real world problem and not a problem in a book, so if you feel I am missing some information just let me know. A ball is flying at 25 m/s The wind is blowing perpendicular to the trajectory at .44704 m/s \rho = \frac{1.17 kg}{{m}^3} Cd = 1/2...
  47. C

    Wind Load Formula: Charles Hutton | A=Fsinx^1.84cos-1

    I'm not sure where to post this, so please excuse me if this is misplaced. I need help understanding how the terms are grouped in this formula for A = pressure normal to the roof. If any of you are familiar with this formula or can link me to a source containing better expressed formulas like...
  48. D

    Adiabatic Wind Descending Homework Problem

    Hi everybody, this is my first post on your forum and i hope someone can help me :) the problem is i can figure out how to approuch this problem :s i do know that the process of the air descending is adiabatic but still i can't get it :( thanks for your help guys in advance. Homework...
  49. B

    The Force of Wind and the Debate on Heat, Energy, and Mass

    i'm currently discussing this with a friend. anyway. here is the conversation: he said It started as "If something doesn't have a mass, it cannot have a force", due to Newton's second law, F = ma (Force = Mass x Acceleration). Logically, if you substitute 0 in for the Mass, you will get a...
  50. E

    Generator types in wind turbines

    What are the percentages of types of generators commonly used in wind turbines? To clarify, what percentage are regular squirrel-cage machines? What percentage are doubly-fed machines, permanent magnet machines, synchronous machines, and so on. I'm looking for a general idea of these statistics.
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