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. J

    Automotive Wind-Powered Vehicle: New Idea & Input Welcome

    Hi : I am new here but have been thinking about this for a while. I am attaching a drawing to hopefully explain my idea. I think a crossflow fan mounted at the rear of the vehicle's roof ( Accross the width of the car's roof ) , protruding partially above it and setup to allow air flow through...
  2. A

    Sizing Wind Turbine Generator - 8,000 Nm's - Help Needed!

    I am attempting to size a wind turbine generator where the torque available is 8,000 Nm's. Can anyone save me doing the calculations? Regards AV8TUR.
  3. R

    A question about temperature and wind motion, and hello

    First of all, just registered, first post. So hi all, just started undergrad course in physics at kent so may pop up here quite a bit :) So, I was just outside, having a smoke, standing in the doorway of the house. Now I've noticed this before and not thought it about as much but the smoke...
  4. J

    Calculating Airplane Velocity and Heading with Wind

    Homework Statement A plane is traveling at 350km/h northeast through a wind that is blowing 134km/h south. a) What is its true velocity and heading? b) What is its velocity directly east? I'm really not sure how to set this up. I need some nice pointers or someone to solve it and explain...
  5. M

    Question about Vectors and how the change in direction from the wind affects it.

    (The National Hockey League has closed its doors. This is the best we can do for sport.) I suggest that you make East the x-axis and North the y-axis. Neither axis is up or down, both are along the ground. Allan is skating East on a flat ice rink at 4.0 m/s. The wind is blowing...
  6. T

    Vertical Axis Wind Turbine Power Estimation

    Hello, Can some explain to me how to calculate the power coefficient of a vertical axis wind turbine. If you explain the steps invloved would be great or any external file location where I could refer. I have below information 1) Lift Coefficient. 2) Drag Coefficient. 3) Angle of...
  7. U

    Length Contraction Ether wind

    Length Contraction "Ether wind" Homework Statement Due to the ether wind, anything that moves along it is "contracted". The Attempt at a Solution Taking L1 to be contracted length, (L1)2 = (L1x)2 + (L1Y)2 = (L10,X/γ)2 + (L10,Y)2But what they wrote is the opposite..
  8. I

    Wind turbine blades and bearing calculation help

    Ok I have a design project that I am working on for the University this semester. Having a bit of problems trying to figure out and issue revolving around the wind force on our savonius blades. We are trying to make sure our blades will rotate with a wind speed of 10 mph. We have the blade total...
  9. S

    How Do Wind Belts Oscillate?

    Have you guys heard of wind belts? How would you model the oscillation of the actual belt?
  10. G

    Does Wind Feel Cold Because of Heat Transfer?

    You now how when you feel a light breeze it feels kind of cool? Why? Atoms are moving faster and they hit your skin with higher velocity so I would think wind would be hotter than normal.
  11. Q

    Why Do Wind Turbines Have a Power Curve Limit?

    Hello, As wind speed rises, the power output of wind turbine also rises. However, after it reaches a certain value (rated power), it levels off, i.e., it doesn't increase any further. According to my teacher, there is a limit to the power generation capability of the generator and hence...
  12. J

    Determining wind velocity vector.

    Homework Statement A light plane is headed due south with a speed of 185km/h "relative to still air". After 1.0hr, the pilot notices that they have only covered 136km. And that their direction is Southeast 45 degrees. What is the wind velocity? Homework Equations Im guessing you have to...
  13. D

    Investigating the Magnus Effect on Solar Wind

    I can't find authorative sources on whether the magnus effect works on the solar wind. I thought the solar wind was mostly particles, not a fluid medium, and therefore it would not. I thought this was the reason for the flat nature of solar sails. If the solar wind acted like a fluid medium...
  14. A

    Mooring line for wind turbine model

    Hello, I am construction a floating wind turbine model which is going to be used in a wave tank experiment this fall. Currently I'm looking for a mooring line for this model. The line will go from the wind turbin down to the bassin floor, where it will go through a pulley and back up to...
  15. C

    Wind speed calculation from a pressure setting

    I have been out of school a long time, so please go easy on me. If the answer is an equation with symbols or letters, could you please help define them for me? I am trying to calculate the windspeed flowing through a tube with circular opening that is 38cm2 when the vacuum creating the...
  16. A

    Questions About Wind: Get Answers Here

    I have a few questions that share a similar theme. 1) Is wind just fast-moving air particles? 2) When you're in a stationary car and it begins to move, does the back of the car push the air particles inside the car forward (I know they're always moving but is there some sort of net...
  17. P

    Wind chill: how to calculate? Is there such thing as wind warmth ?

    Wind chill: how to calculate? Is there such thing as wind "warmth"? If it is really hot outside, and the air were warmer than your skin, would you feel warmer when it blows on you? Would there still be some sort of chilling effecT? I'm guessing it's like basic convection. If the the fluid...
  18. P

    Does wind help a runner run laps faster?

    If you are running on a circular/elliptical track, and wind is blowing in one direction, will it have a positive effect? I'm thinking the "macro" forces should cancel out. However, when you're running against the wind, I think you'd get some turbulent air currents, whereas when you're...
  19. S

    Ansys Guru Needed: Troubleshooting Offshore Wind Turbine Tower Units

    Hi! I'm doing my master thesis about designing a offshore wind turbine tower for subarctic conditions and I have a major problem with units I'm not much familiarised with Ansys, so I use Ansa as preprocessor and launch the solve in Ansys The problem I have is in units. I'm using Ansys...
  20. K

    Wind turbine efficiency question

    If we look at wind turbines used for power generation, they typically have 3 blades, and the blades are very slender compared to the blades of a house fan. I don't understand how such a slender blade can capture a significant amount of the wind's energy. The energy available in the wind is...
  21. A

    Seeing the Wind: Is It Possible?

    My apologies if this post hit the wrong topic. I was wondering if it's possible to "see" the wind by means of an spectrometer or a similar device. I'm aware that light passes through air and it does leave behind some portion of it's wavelength through absorption, and this is invisible to the...
  22. Y

    How can wind stiffness be calculated for a MDOF model using wind speed data?

    Hey guys I am looking for the solution to replace the spring in MDOF model with wind stiffness or air stiffness if to build a MDOF model of wind. What I have now is only a wind speed data matrix. Anyone can provide some equations of calculating wind stiffness and some clues maybe...
  23. M

    Wing and wind turbine blade aerodynamic center?

    Hello everyone, Now i am trying to model wind turbine blade using solidworks. I have the airfoil coordinates at each section of the blade, but the coordinates are distance per chord (x/c,y/c) so i have to scale it using the calculated chord. When i scale it with respect to the origin -...
  24. J

    If the moon was vapourised, would it recondense or get blown away by solar wind?

    If the moon was vapourised, would it first recondense or get blown away by solar wind?
  25. M

    Calculating Reynolds number in wind tunnel

    when calculating a Reynolds number for an obstacle in wind tunnel Re = air density * air velocity * D / Dynamic viscosity D here is the characteristic length of the immersed body ( frontal length ) 2 dimensional problem Or the Hydraulic diameter which relates the tunnel dimensions to the...
  26. T

    Wind resistance on a rapidly rotating flywheel

    I am simulating a rapidly rotating (horizontal axis, if that makes a difference) flywheel. The software isn't too sophisticated w.r.t. wind resistance, unfortunately, and seems to use the diameter of the rotating body as one of the main parameters, in addition to the velocity of the rotating...
  27. B

    Meteorology question: Cloud direction vs wind direction?

    Sometimes, but not always, the wind direction (as given by weather.com for my location) is exactly the opposite of the cloud movement. For example: the wind may be given as NW but the storm clouds are coming out of the SE. Almost always the wind direction given by weather.com is corroborated...
  28. C

    G-force of wind on a persons body.

    After doing some work with a painter friend we were coming home and I put my arm outside of the window as we were going 70 miles an hour. Wondering what the g-forces would be on my arms and hand? Thank you
  29. B

    The affects of Lenz's Law on Wind Turbines

    Hi, If an electrical generator induces a current that opposes the shifting magnetic field that creates it then why don't the wind turbines on wind farms just stop turning after a while? Is it because they are not directly connected or drawn on by electrical devices? Thank you all in advance!
  30. E

    Micro wind propeller design

    Hi everyone! I would be so happy if someone could help my little brother and I answer a question for a science project that we have researched ineffectively for hours. We hope to design the most efficient propeller for micro-wind turbine. The purpose of this propeller is to naturally rotate when...
  31. K

    Wind Turbine Energy Yield Calculation at a Given Site

    Homework Statement I need to find how much energy will be produced (at least approximately) at a site with the following characteristics (this is taken from the German Renewable Energy law): “The reference site shall be a site determined by means of a Rayleigh distribution with a mean...
  32. 5

    How Do Distance and Angle Affect Wind Drag on a Sheet?

    Homework Statement angled piece of sheet set at various distances to a set fan, the sheet is placed on scales and they measure the amount of force the wind creates. There are noticeable differences at the different distances and angles. Homework Equations wind force and wind pressure...
  33. 5

    Wind force, drag, something :v

    Heyy uh I have this problem I'm confused about; there is a body at rest (a sheet of cardboard set at an angle to electronic scales) and a fan blowing at the surface area. There is noticeable difference when I adjust the speed of the fan, the angle it sits at and the distance to the fan. Anyway I...
  34. B

    Can wind chill cause frostbite at above freezing temperatures?

    Two questions. I have read that wind chill is a measurement (or calculation, more accurately) that describes how cold the wind feels, even though the wind isn't actually colder than still air. What I am wondering is why isn't the wind actually colder? If it is moving faster it is lower pressure...
  35. A.T.

    Directly UPWIND faster than the wind

    The Blackbird Landyacht which went 2.8x faster than the wind directly downwind, has been outfitted with a turbine and is now going directly upwind, faster than the wind. The official numbers are not in yet, but estimates are 1.5 - 2x windspeed. The DUWFTTW blog...
  36. Z

    Wind Mill Damage: Calculating New CG

    I have a weird question that I can't figure out where to start. It's been a while since physics: A wind mill has a hub and 3 blades the hub weights 45000 lbs and each blade weighs 14000 lbs. the CG is at the hub when the assembly is intact. We had a storm and 2 of the 3 blades broke so...
  37. T

    Can Extremely Low Wind Speeds Impact Weather Predictions and Climate Models?

    How slow can wind blow on Earth (and elsewhere) before local obstructions (trees, hills, buildings) essentially stop it? How low a wind velocity can be measured, and does the wind velocity spectrum extend to zero? I was wondering about wind speeds in the 0 to 10 centimeter/second range. I...
  38. E

    Exploring Adiabatic Wind in the Rocky Mountains

    Homework Statement Adiabatic wind. The normal airflow over the Rocky Mountains is west to east. The air loses much of its moisture content and is chilled as it climbs the western side of the mountains. When it descends on the eastern side, the increase in pressure toward lower altitudes causes...
  39. F

    Kinematics Vectors and cartesian coordinates. Plane with wind blowing.

    Homework Statement An airplane flies at an air speed of 300 miles per hour, in the direction toward southwest. There is a head wind of 75 mi/hr in the direction toward due east. (A) Determine the ground speed. (B) Determine the direction of motion of the plane, expressed as an angle...
  40. X

    Finding the velocity of the wind

    Homework Statement An airplane travels N40∘E at an airspeed of 1000km/h. Measurement on the ground shows that the plane is traveling N45∘E at a speed of 1050 km/h. Calculate the velocity of the wind. Homework Equations Vg = Va + Vw The Attempt at a Solution so i know we're...
  41. V

    Understanding Wind Cup Anemometers: How to Determine Wind Direction

    How is it possible without knowing the wind direction to work out which direction the cups are moving (ie clockwise or anticlockwise round) simply by looking at a diagram of a wind cup anemometer? Does the wind always blow into the hollow end of a cup and then each cup moves forward and the...
  42. J

    Space Physics (sun and solar wind) problem

    Homework Statement If, (average solar wind properties at Earth's orbit) Proton density = 7 cm^-3 flow speed=400km/s almost radial electron density=7.5 cm^-3, proton temp=2*10^5 Kelvin He^2+ density= .25 cm^-3 electron temp=1*10^5 Kelvin Magnetic field=7nT Find flux through sphere and flux...
  43. G

    Relationship between Drag Force and Wind Speed

    The drag force can be affected by the velocity of the object relative to the fluid. Does that mean the wind affects the drag force, since it changes the velocity of air particles?
  44. J

    Solar wind interaction with Earth's magnetic field

    I'm currently doing a project on how the solar wind interacts with the Earth's magnetic field, but I'm having a hard time grasping the concept of the plasma emitted by the Sun and how it shapes the Earth's magnetic field. I read somewhere about a simple mirror dipole approximation (I'm guessing...
  45. S

    The single strut in wind tunnel test

    I will do research on the vertical single strut. i want to ask if there is something interesting to study?
  46. Z

    Calculate torque for a wind turbine

    density=1.2041 kg/m^3 Power 1.65 MW Rotor radius (blade length) = 37m calculated swept area = 4,301 m^2 wind speed 12m/s the rotor speed range is upto 20rpm i want to calculate the torque but not quite sure how to go about it Thanks for any help!
  47. A

    Wind Turbine Design: High Output for Low Wind Speeds

    please excuse the writing in some of these messages as I am typing this from my phone, but I am looking to build a high output wind turbine. I have a few questions. I am a high-school senior and have a large understanding in physics. my idea involves a 12 wing rotor as wind speeds are low in...
  48. T

    Wind Turbine generator on a camper

    I am building a "Tiny Home" on an old camper travel trailer. I am using all recycled materials and any leftover building supplies I can find. I am going to use solar power to generate most of my electric power (lights, outlets, etc.). I am considering using a hybrid system and utilizing wind...
  49. B

    Definition wind tunnel blockage ratio

    Hello, I’m designing a 2D wind tunnel model for my master thesis. It will be a profile equipped with a fixed hinged trailing edge flap. I’m going to measure at different angle of attacks and different flap settings at low speeds (about 70 to 100 m/s). The aim is to measure steady and unsteady...
  50. B

    To what extent is wind due to quantum indeterminacy

    I know that wind is the result of fluids being drawn from high pressure to low pressure among other classical forces. Wind though is highly chaotic and random. Each molecule of air is essentially unbound to other molecules. Is the movement of these molecules partly due to QI? Actually, to...
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