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.

View More On Wikipedia.org
  1. B

    Wind Turbine Reynolds number calculation verification

    Homework Statement Hi guys, I just wanted to verify my calculation of a reynolds number of a wind turbine. I understand that the reynolds number will vary in a spanwise direction along the blade due to changes in the characteristic length(chord width) and velocity(due to the tip speed...
  2. Y

    New to building a wind generator -- Need help

    I thought it is easy when I was watching all sorts of instruction videos. However, now I have Fisher and Paykel stator and rotor, and I cannot solve how rotor is suppose to spin. The magnets are so strong that I do not think any wind will be able to move it. When I received my parts, I had hard...
  3. M

    Wind Turbine with Generator & Gearbox on the Ground?

    I have often wondered why conventional large wind turbines have evolved with their generators and gearboxes in the nacelle at the top of the tower where they are hard to reach and maintain. Despite this fact, I wish to believe that there may be benefits to a conventional horizontal shaft wind...
  4. B

    How does varying roof angle affect lift in wind

    Hello guys! New here. Grade 11 student. I'm working on a project to investigate how roof angle relative to the horizontal vary with lift, according to Bernoulli's principal. The purpose is to reduce injury in storms. Problems are: Wind blows in all direction and I was thinking about...
  5. B

    Wind and rain sounds -- how to make from basic sources?

    ok I have a FFT filter ( lowpass and highpass), white, brown, and pink noise generators. How do I use all these things to make wind ,rain, and ocean noise ? I am told there is a way.
  6. A

    Some questions regarding wind turbine

    Hey guys, I am starting with the course for wind energy and although i have a pretty good knowledge until now , but I am still confused about somethings which i hope some of you will help me to clear :) Q1. Ok ... so why is there a twist in the blade? I mean wouldn't it be much...
  7. R

    Wind Turbine Power Calculation Equations

    Glad it's Friday? I will be if you can help me with this :D : I'm trying to understand an equation about calculating the power extracted by the blades of a wind turbine. I have spent a couple of hours going over it but still not making much more sense. I'm trying to find out why P =...
  8. davidbenari

    Forming a standing sound wave in a wind instrument

    So I've had this question bugging me ever since I saw sound at physics class: How is it possible to match the resonance frequency of a column of air in an organ pipe and form a standing sound wave by simply blowing air into the column? The main reason I see this problematic is because I...
  9. A

    Building Horizontal-Axis Wind Turbine: Testing Blade Designs without Generator

    Good day! I was thinking of building a horizontal-axis wind turbine and testing various blade designs but i can't afford a generator to test the power output of each variation. Is it sensible/possible to get the output without a generator? Can equations in finding torque be used? Thank...
  10. G

    Dual axial flux PMG wind turbine

    I am making a small vertical savonius type wind turbine and would like some general rule guidelines. I am using 14awg magnetic wire--70 turns (2"oval) and ceramic block 1" x 2" x.375" magnets. I am hoping to get the most power possible at lower wind speeds. Is there a rule that states a...
  11. gfd43tg

    Wind blowing in face when driving

    Why does the wind blowing on you as you drive with the window down feel cool? It's temperature should be the same as stagnant air if I wasn't driving. My guess is that it has to do with convection because the air has a velocity relative to the driver and there is a heat transfer coefficient of...
  12. A

    How to Calculate RPM of Wind Turbine generator

    I am going to design 10 kw, Permanent Magnet, Direct Drive Wind Turbine Generator. The main problem is, how to determine the rotational speed of the Wind Turbine. This is important for me because I have to design the PMG and its rated rpm values...
  13. Dotini

    Solar Wind Modulates Lightning - Mechanism Unknown

    http://iopscience.iop.org/1748-9326/9/5/055004/article http://www.bbc.com/news/science-environment-27406358# Activity on the Sun is sparking lightning strikes here on Earth, a study suggests. The finding was surprising, said Dr Scott, because it had been thought that an increase in the...
  14. M

    Wind loading due to gusts; resultant torque on a 6' parabolic dish

    Hi, We had a company do a pointing error analysis on a proposed pedestal system, on which is mounted a two-axis (azimuth and elevation) 6 foot parabolic dish. I estimate the distance from the rotation axis to the apex of the dish to be roughly 43 inches. Among the error sources are errors due...
  15. W

    Wind speed acting on a moving vehicle

    Hi all, newby here that could do with a little help. I'm doing a college project and need to work out the head wind speed in m/s that a vehicle would encounter at a various range of speeds in mph, for example a high speed train, so I can compile a graph of the data ranging from 10mph up to...
  16. A

    Acceleration of the tips of wind turbine blades

    Homework Statement A wind turbine has a rotor (its rotating section) which has a moment of inertia I = 1.26 × 10^7 \text{kgm}^2. At peak output, with the rotor completing 0.25 \text{ revolutions per second}, the turbine produces a power of P = 3\text{MW}. The tips of the rotor blades sweep out...
  17. J

    Calculating the turning moments for a passive wind turbine under yaw

    Hi I have been looking for some simple equations that describe the turning moments on the rotor as wind direction changes. I know this can be relatively complex but I am looking for simplified equations. Has anyone got any information where I can find these? The wind turbine is a small...
  18. J

    Effect of wind turbine yaw on rotor rotational speed

    Hi From what I understand as the rotor yaws, there are gyroscopic forces that act upon it and the magnitude of these depends on the speed of yawing (e.g. 10 degrees per second). What happens to the rotor rotational speed during yawing? Does it slow down? Is the aim to slow down the rotor...
  19. J

    Analysis of a wind vane/weather vane

    Hi I am trying to create a model to simulate the motion of a weather vane. It basically looks at the wind direction and as the wind direction changes, the objects responds by trying to align itself parallel to the wind. First of all I am looking at the force perpendicular to the pivot...
  20. W

    Optimizing Wind Turbine Efficiency: Exploring the Impact of Blade Size and Shape

    Hi - I know someone must have thought of this already, so maybe you can help me understand. When I look at some of these modern wind turbines, the blades seem massively long. I see this lumbering set of blades moving slowly and I imagine that the bulk of the wind does not even touch the...
  21. O

    Experimental Measurements in Wind Tunnel

    Hello everyone, the forum looks great and I have been reading it for a long time, but I have only registered. I am writing this post because I have to analyse two flow fields in a wind tunnel. 1) The first flow is generated from a helicopter blade, with Re=2000000, Mach=0.92 and...
  22. S

    What is the Relationship Between Solar Wind and Kinetic Energy?

    Homework Statement At what rate does the solar wind carry kinetic energy away from the sun? Give your result first in watts, then as a fraction of the Sun's luminosity in photons, L=3.8*10^26 W Homework Equations KE=(1/2)mv^2 mass loss of sun- Msunloss=4πr2vρ The Attempt at a...
  23. A

    Work-Energy: Determining x- and y-components of wind force

    Homework Statement Homework Equations Constant acceleration equations: Δx = v,xi *t + 0.5*(a,x)*t^2 Δy = v,yi *t + 0.5*(a,y)*t^2 K = 0.5*m*v^2 U = mgh W,nonconservative forces = ∫ ∑ F dx Conservation of Energy: K1 + U1 = K2 + U2 ∑F = ma The Attempt at a Solution (Note that in my notation, I...
  24. Z

    Direction of wind for forced convection

    I am wondering if in a case where the air velocity comes from one face as shown in the picture. Can I assume the whole area going along the channel will be subject to the same convective coefficient? Thanks
  25. A

    Wind in a rotating space settlement?

    Imagine a cylindrical space settlement. It spins about an axis to create pseudo gravity for residents, who will think that radially outward is "downward". The shape of this settlement is a toroid with a rectangular cross section. Air is pumped into make a habitable environment. Then...
  26. C

    Forces on skier: slope friction and wind

    [b]1. The problem statement: Slick is skiing down a 27 degree slope (above horizontal) into a headwind (parallel to the slope) of 8N. His mass is 78Kg. The coefficient of friction between the snow and the skis is 0.11. What is the resultant force? If the coefficient of friction...
  27. A

    Can a wind tunnel simulate a scramjet?

    Can a wind tunnel get up to scramjet speeds; ie. Mach 6-12?
  28. R

    Ideal coil size for a low wind turbine.

    I can't find anything I can make heads or tails out of so if you guys can help I thank you. I would like to design a wind turbine and be able to get as much power as I can out of each of it's coils. If I start with a magnet that is 1.1811" in Diameter and it is .125" thick with a grade of N52...
  29. J

    Exploring Buoyancy & Wind Effects on a Weather Balloon

    Hello there, A weather balloon is released, and its acceleration in the z-x-plane, a is governed by a buoyancy force, B, which is constant in the k-direction. gravitational acceleration, 9.81 m/s^2, in the k-direction, and FD, which is is like this: F_D = -D|\vec{v}|\vec{v} where D is some...
  30. P

    Wind induced waves in narrow irrigation canals

    Hi, We are trying to estimate the likely maximum wave generated from wind blowing along an irrigation canal. We will subsequently estimate runup and the required freeboard to prevent overtopping. Our canal is ~ 5m deep, has 1:2 side-slopes and a 4.6m wide base. The canal is aligned with...
  31. J

    General tendency of a homogeneous floating balloon in a wind current

    Homework Statement Any floating homogeneous balloon in a planar uniform wind current will always "tend" to present to the wind flow a section of maximal drag. 2. The attempt at a solution I have three possible solutions to this "problem": 1- Speed gradient justification: When an object...
  32. D

    Why do Wind Turbines have such large blades

    This might sound like a ridiculous question and I am sure it is (they don't build them like that for fun) but why on Earth do they? I read an article that said the new PMG style turbines only require the shaft to be rotating at 16rpm to generate up to 8.6MW. Is there so much resistance that...
  33. N

    Wind velocity and aircraft (answer check)

    Homework Statement You’re a pilot beginning a 1500-km flight. Your plane’s speed is 1000 km/h, and air traffic control says you’ll have to head 15° west of south to maintain a southward course. If the flight takes 100 min, what’s the wind velocity?The Attempt at a Solution veffective south =...
  34. Q

    Calculating Load for a Mini Wind Tunnel?

    Hey guys, so I'm building a mini wind tunnel and I would like to calculate the new RPM,HP and Torque since the propeller will act as a load and change the specs of the motor(note I'm using a air wrench as the motor as it's all I had around and have disabled the impact motion) the current specs...
  35. J

    Some numbers with wind turbines

    http://en.wikipedia.org/wiki/GE_Wind_Energy The rotor swept area is 4657 m^2, and wind speed is 11.5 m/s. Produced power 1.5MW. I assumed that the air density is 1.2kg/m^3, and computed, that the theoretical upper limit for produced power would be 4.25MW. This was obtained by computing the...
  36. L

    Pressure due to a perpendicular wind

    Sorry to ask another question :/ Homework Statement Consider the change of momentum. A wind (of speed v) acts perpendicularly to a wall. Show that the pressure do to this wind acting of the wall is v2ρ, where ρ is air density. Hence show by suitable integration that the torque about the...
  37. J

    Where Can I Find UK Companies That Provide Wind Tunnel Model Mold Services?

    Hi, I am currently researching methods available for manufacturing a half-span wing model (approx 0.5m span, low sweep delta wing of varying cross section) to be used in wind tunnel experiments. A recent paper suggested the use of epoxy and micro glass beads injected into an aluminium mold...
  38. A

    Harnessing Wind Energy From a Car for Fuel Efficiency

    First of all, I have read some of the previous posts that related to this topic, but they are closed. I am not looking to solve the world's energy crisis, but I was wondering if there was a way to harness some of the energy given off as friction from the drag of a car. I was looking at some of...
  39. K

    Would wind tubine on moving automobile pomote inlet efficiency?

    Question as the title above ! Could we use the wind turbine to compress the air into engine cylinder as the exhaust compression tubine does ? Thanks all for replying !
  40. J

    Calculating Maximum Height and Equilibrium Height of Pendulum with Wind Force

    Homework Statement A ball of mass m = 300 g is connected by a strong string of length L = 80.0 cm to a pivot and held in place with the string vertical. A wind exerts constant force F to the right on the ball as in the figure below. The ball is released from rest. The wind makes it swing up to...
  41. P

    Energy source for hot place on cloudy / rainy days without wind?

    Say you're in a place either 15 degrees north or south of the equator where average temperatures are over 25C (77F), a large majority of days are either cloudy or rainy and there isn't any wind. You need 50Wh a day for your needs and the battery you have happens to have a capacity of 50Wh as...
  42. C

    Choosing a generator for mini wind turbine

    Hello physics forum, I am currently trying to figure out how to pick a generator for a horizontal axis mini wind turbine based on specs. I plan on buying a DC motor to use as a generator with blades directly attached to motor shaft. My goal is for the motor to be most efficient at 25mph wind...
  43. D

    Wind Power solutions for High Rise buildings

    For high Rise Buildings,say above 30 floors,wind energy could be too ample to be wasted. So what kind of study has to be carried out in order to know the feasibility of installing Wind turbine above a building? What will determine the power output of this turbine?
  44. D

    Repeating Water Tunnel Studies in Wind Tunnel

    Is there any significance in repeating a water tunnel study in a wind tunnel? If so, would the results be publishable or would it just be considered repetition of a previously published water tunnel study?
  45. N

    Energy and speed of a wind turbine

    Homework Statement Modern wind turbines can convert up to 30% of the kinetic energy of the incoming wind blowing through their blades to electricity. Assuming that the wind at a proposed offshore location blows steadily at 20 knots, how much electrical power can be generated from a turbine...
  46. S

    How does solar wind effects Geomagnetic Field?

    Solar winds contain plasma, which are charged particles and carry Sun's magnetic field orientation, when those solar wind hits toward Earth, does anyone have any suggestions on how those plasma affects on Earth's magnetic field? and how this energy converts into different forms on Earth? Does...
  47. T

    Generating electricity with wind

    I am building a scale model wind farm with 10 Brushless DC motors. Each motor is rated 12v and 1.3 amps. Provided that I can generate 12 V on each motor, what is a realistic amount of power that I can generate? Thank you.
  48. M

    Increased mass (inertia) affect on wind drag

    Okay, so the scenario is a passenger car, traveling on the highway. As a general rule, I say that increased weight (mass) will have a beneficial effect on MPG (IF tire pressure is increased so that rolling resistance is reduced to compensate for the increased weight), ONCE the vehicle is up to...
  49. S

    Cold & Hot Wind: What's the Difference?

    What's the difference between cold moving air and hot moving air? For instance, suppose you put two fans, of the same type, each in one room. One room is cold because the walls are covered in ice and one room is hot because due to the effect of heaters. Turn both fans on and the air flow, the...
Back
Top