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. M

    Relationship Between Wind and Pressure

    I read in a book that the pressure caused by a wind blowing against a structure increases as the square of the wind velocity. I cannnot logically understand how that makes sense, and I can't think of any equation to support it. Can somebody please shed light, conceptually or mathematically, as...
  2. S

    Torque in Wind Turbines: Calculating Power Output

    【 mod note: moved to H/W forum so homework template is absent 】 Dear all i am trying to calculate torque in HAWT from the measurements using Rope brake dynamometer set up with a blower. i had wound a string over the turbine shaft. The string is connected to a spring balance on its one end and...
  3. A

    I Wind Force on Curved Surfaces: Investigating the Drag on an Upright Cylinder

    Hey guys, I'm trying to prove to a friend something but I couldn't find a proof online. Imagine wind coming in from the side and hitting an upright cylinder. We're trying to find the force exerted, which then requires which kinda of cross section to use. I think the best way to calculate it is...
  4. petef

    Accelleration of a static body in wind

    Homework Statement I drop a 50mm sq concrete cube fom a notional tower into a steady horizontal wind stream of 10m/sec. Homework Equations How long before the cube reaches the wind spead What is the accelleration How far will the cube have traveled down range The Attempt at a Solution
  5. G

    Understanding Wind Turbine Efficiency: Exploring Betz's Law and Other Factors

    I am trying to understand wind turbine efficiency and the phenomena of Betz's Law. I have a basic grasp of Betz Law which says the maximum efficiency of a wind turbine is 59 % energy capture of the wind swept turbine area (more or less in those words). I understand that when the wind hits the...
  6. B

    Making a wind turbine, how to stop it overcharging battery?

    Hi, I plan to make a simple 12v-battery trickle charger wind turbine that I will put on the roof of my garage and connect to my jetski to keep it topped off during winter when my solar panel is performing poorly. I have a 24v Motor I will use and will use a bicylce wheel for the "blades". I was...
  7. AntoineCompagnie

    How can a lateral wind gust create a lateral acceleration?

    Hello everyone! I have some difficulty to understand what momentum actually is, can you help me understand this concept? 1. The problem statement, all variables and given/known dat If a quadrotor of mass $1kg$ flying along the positive $x$-axis at a speed of $4m.s^{-1}$, why would a wind gust...
  8. S

    I Gravitational Waves Vs. Aether Wind

    The Michelson-Morley Experiment (as depicted in the scishow YouTube video "The Greatest Failed Experiment Ever") which was used to test for the effects of 'Aether Wind' appears to be almost, if not completely, the same setup as the one used in a gravitational-wave observatory. Why is the success...
  9. Curiosity and a Cat

    Just a Thought About Tornadoes and Wind Turbines

    I was asked a question and since I have no solid answer I'm re-asking it here. The question was about wind turbines and tornadoes/hurricanes. All that raw energy and we've never tapped into it. Here's the question: Why? I understand the difficulties inherent with a project like this but the...
  10. P

    How does the solar wind affect Earth's atmosphere?

    In the past many of us have read Mr Faraday calculated the “weight” of photon’s striking the surface of the Earth per acre at something like 4 and ½ ounces. Today, frequently we hear stories on the subject of the Sun's solar wind and how it is tearing away the Martian atmosphere and even...
  11. Square1

    I Plane slides on ice because of wind

    I found this clip on youtube of a plane getting pushed on ice due to strong winds. Have a look. I guess I just want to hear some comments about what is reallly going on here. How we can estimate the force of the wind pushing, what chance the ramp agent has of holding the place himself if say...
  12. C

    Confusion regarding the speed of sound in wind

    One of my students asked me the seemingly innocuous question of "how does wind affect the speed of sound?". My immediate thought was that the velocity of the wave would be the vector sum of the velocity of the wind and the velocity of sound waves in still air. However, upon further reflection I...
  13. B

    A Is Solar Wind Formed by Planetary Resonance and Solar Cycles?

    so the solar wind is the result of resonance of orbiting planets, and solar cycles too, after this paper [Link to crackpot paper deleted]
  14. J

    Integrating the solar wind equation

    Hi, eveyone have been struggling to do this problem for a long time now, figured it is something very simple I am missing so thought I should ask here. 1. Homework Statement Parker's solar wind equation is given after some manipulation as: (v - (Cs2 / v) dv/dr = 2 (Cs2 / r2) (r - rc ) where...
  15. A

    I Pluto's interaction with solar wind

    Do you think that new discoveries about how Pluto interacts with the solar wind suggests that Pluto should be reclassified as a planet?
  16. Tom MS

    B Does the Coriolis Effect Occur When Wind Moves Horizontally?

    I'm trying to get an understanding of the Coriolis effect, and I understand it when the wind moves longitudinally (North-South). Basically, the wind has a certain horizontal component of its velocity due to the rotation of the Earth, and as it moves North or South the rotation of the Earth...
  17. L

    Implementing wind into projectile calculation.

    Homework Statement Calculate distance of a rock thrown at certain angle, velocity and wind speed/direction. Homework Equations I'm using this: 2(vi^2)sin(theta)cos(theta)/9.8 to calculate the distance of the throw. How could I implement a wind value and direction into this equation? This is...
  18. Alfreds9

    Water evaporation, temperature, wind and heat capacity?

    Hi, I'd like to know how I'd put together, either elegantly or at least in physical terms, that surely water evaporation in a large pool of V volume and S surface is influenced by wind (increased by it as opposed to having side barriers), temperature (increased by direct sunlight as opposed to...
  19. PD Chant

    Vertical Wind Tunnels using green technology

    I wish to create a state-of-the-art vertical wind tunnel for indoor skydiving. By state-of-the-art I mean using green technology to create the power necessary to push air, and I would like to reclaim as much energy I can from the movement of air, drive shafts, and anything else I have not...
  20. I

    Do Wind Turbines Significantly Alter Weather Patterns?

    As more wind turbines are installed worldwide, I was wondering how much of an impact on weather they could/would have. (Full disclosure: I am not trained, merely an interested non-scientist) Collectively, wind turbines are collecting considerably more energy than Lorenz's butterfly, so could...
  21. Y

    Wind Turbine and Power Generation

    Working on a wind turbine for a class project and making an attempt to add a brake. The idea is that the turbine will generate power at a certain wind speed and if the wind speed is increased, we would slow the turbine with a mechanical brake. We're using a 10V low-torque motor and have created...
  22. S

    I Amount of energy in wind blowing through a tube

    If wind was blowing through a tube at 15 kilometers an hour from an open end 2 meters wide to a tapered end only .3 meters wide how fast would the air be moving when it exits the pipe? I'm using the equation Q = v * A (Q is flow, v is velocity and A is area of the tube opening) but is that the...
  23. Neeps

    I What is the Definition of Apparent Wind Angle on a Boat?

    Hi. I'm working on a digital filter, whose computations are dependent on calculating apparent wind. But I'm not entirely sure if I'm using the formula correct, because i find the description of variables some what vague. Would love if someone please could point out, what the alpha angle is...
  24. M

    Wind turbine to charge 12V batteries

    I have a mws freedom pmg 12 volt 1600 watt PMG with falcon mach 3 blades. Live in city so turbine is only 12ft off ground. Don't get good wind. Can I use a 24 volt pmg to charge my 12 volt battery bank? Have charge controller that can handle high voltage and will dump at 14.5 volts. Also have...
  25. Erika Brown

    Wind Turbines and Conic Sections

    I am working on a project for my precalculus class. They are going to study wind turbines and design a wind turbine blade. I am trying to understand the math behind wind turbines myself. Can I relate wind turbines to a study of conic sections?
  26. F

    Exploring Wind Tunnel Data Collection Methods for Physics Coursework

    I'm nearly at the end of my preliminary testing for a wind tunnel in my A2 physics coursework. My question for my project so far is: "Do different shaped objects exhibit different properties under the influence of high speed air". For my coursework I need to measure or observe something to get a...
  27. ATY

    Chord length and radius of a wind turbine rotor blade

    Hello, I have a question about the chord length of rotor blades from wind turbines. I do not really understand what the difference is to the radius of a wind turbine. I can not find a real explanation, but it seems to be very important. I know that the formula of the chord length depends on...
  28. A

    How Can I Improve My Homemade Wind Turbine's Charging System?

    Hello! I recently built my own wind turbine. The motor is from an old treadmill, the blades are 5 pvc blades i made from scratch. So I built the whole thing, but the circuitry doesn't work so its just basically looking cool and doing nothing. My roommates are giving me crap about it, but they...
  29. Recycler

    Wind turbine with increased efficiency

    Wind turbines apparently now produce electricity only at some minimum wind speed.In my conception,the wind pressure of a lower wind speed is used to exert a force on a diaphragm or vane which stores torque in a spring or other mechanism,This torque could be used to help overcome the initial...
  30. E

    Help to form questions regarding wind flow/convection

    Hello! I'm not sure if this is the right forum for this topic, but my question is very general, not a textbook problem or something like that :) . I work in Comsol where I have imported the topography of mount St Helens and I simulate wind flow around the mountain (as laminar flow) and also...
  31. K

    Wind turbines turning in no wind?

    So last week I was returning from a holiday (by car) and on the way I saw a field with about 20 wind turbines on it. They were slowly turning, as usual. At first it seemed normal but I suddenly realized, by the open window of the car, that there was no wind at all. So I wondered if there was an...
  32. F

    How do I determine the exact shape of an airfoil blade for my wind turbine?

    I'm currently doing a project in my tech class where a partner and I have to create a wind turbine. We've decided that we are creating a vertical axis wind turbine, that we are creating the base out of PVC, and using three airfoil shaped blades that will be created via cnc milling. I have a few...
  33. M

    Wind Turbine Effectiveness Project

    Hello, I am creating a wind turbine project that will be very simple to do, hopefully. I already have an old turbine that came from a camera in a airplane some years ago. I need to produce electricity with my turbine, obviously, and before I create my design, I want to ensure the effectiveness...
  34. L

    Temperature & Wind Chill: Why Does It Feel Colder?

    Hi all, so when you heat something up the molecules begin to move faster. This is seen when you steam a tea kettle. So my question is when its very cold outside and there is no wind, it is much more comfortable then when there is cold wind whipping about your body. If molecules moving faster are...
  35. Justice Hunter

    Limit of Wind Speed on Planets: Factors and Upper Bound Explanation

    Besides solar wind, what is the limit of a natural wind on planets? I know it's based on rotation and atmospheric pressure differences, but is there an upper limit to how fast wind can get on a planetary scale? I would imagine that the speed of sound would justify a limit, but that doesn't...
  36. O

    Why Does Bernoulli's Equation Apply to Wind Tunnels?

    I hope this question doesn't have too obvious of an answer. Basically, I still cannot grasp why Bernoulli's equation applies for wind tunnels and pitot-static probes. According to my textbook ("Introduction to Flight" by Anderson), Bernoulli's equation holds only when comparing two points...
  37. B

    Design a wind turbine experiment at the High School level

    Homework Statement [/B] Plan an investigation to evaluate wind power as an energy source with equipment: • model wind turbine • multimeter to measure the voltage generated • anemometer to measure wind speed • hair dryer to generate wind power, set on cold • metre rule to measure...
  38. S

    How to design a wind axial turbine working with an air stream....

    I want to design a wind toubine ,I know the wnd vel,I need certain amount of power ..How to design it and how to calculate at which rpm will it rotate to deliver my required power?
  39. J

    Effect of wind speed on running

    Hi guys, I'm an arts undergrad student with very little knowledge of the sort of physics I'm about to ask. I was wondering if there is a calculation to work out the differentiation between running at a particular speed say 10mph against wind coming towards you at 15mph. As well as it being on...
  40. N

    Project: Charging devices with Eolic (Wind) Energy

    Good evening, everybody, I'm new here so if I made any mistake, I apologize in advance. I've been thinking in a project from a while now and I want to share it with you seeking for your help and wisdom. Basically, I want to build a small wind turbine in order to charge a smartphone or a tablet...
  41. M

    MHB Finding the speed of the wind and an airplane in still air

    Flying against the wind, an airplane travels 3420km in 6 hours. Flying with the wind, the same plane travels 2670km in 3 hours. What is the rate of the plane in still air and what is the rate of the wind?
  42. G

    Wind Turbine, wind direction, air direction, drag direction?

    In the aeroplanes, the drag is in the opposite way of the direction of the aeroplane. My questions for wind turbine: 1) Why "wind speed" and "the drag on the blade" is in the same direction? Shouldn't be the opposite? 2) Are freestream velocity and the wind speed same thing? 3) Are the drag...
  43. R

    Heating water with a wind turbine

    Hello, I know there is a similar topic but it has been closed. It is about a wind turbine that generates wild AC from 0 to 240V(open voltage) for a maximum of 1500W. Instead of using a charge controller, a battery bank and an inverter I would like to connect a water heating element directly to...
  44. ElegantSir

    Law of Conservation of Energy of a wind turbine

    Homework Statement "identify the type of energy conversions present in each of the following situations. Some questions may use multiple types of energy." 1) a wind turbine producing electricity 2) two children sliding down a hill on a toboggan 3) a toaster oven browning a bagel Homework...
  45. irhum31

    How much water remains as ice when wet clothing is dried in dry wind at 0°C?

    Homework Statement Wet clothing at 0°C is hung out to dry when the air temperature is 0°C and there is a dry wind blowing. After some time, it is found that some of the water has evaporated and the remainder has frozen. Estimate the fraction of the water originally present in the clothing which...
  46. Zeynel

    Wind turbines with many small generators

    Hello, This is not a homework question. I'm not a student. In fact I'm retired. The other day, I was passing by a wind turbine. I thought "wouldn't it be better to have hundreds of small generators with small wings connected together instead of one huge generator with huge wings?" But I did...
  47. C

    How does wind affect an airplane's deceleration?

    When I see a paper where it is explained the wind effect on an airplane, I always see a kinematics problem. Now I'm interested in calculating the wind effect starting from the force that the wind exert on the aircraft surfaces. I know that F= 0.5 * rho * V2 * A * C and I also know that if we...
  48. L

    What cosmic "wind" is beign referenced?

    Hi, The extract below is from a paper on ARXIV that I was reading recently. In this paper (and a number of others that I have read recently) there are a number of references to "wind" in a cosmic context. What is this wind? I have tried to do a number of searches to try to find out, but I can't...
  49. RedDelicious

    Optimizing Airplane Direction in Windy Conditions

    Homework Statement A pilot with an airspeed of 500 km / hr wants to fly from City A to City B (which is exactly 700km North of City A); however, there is a wind from the West at 50 km / hr. In which direction should the plane fly in order to arrive directly at it's destination. Homework...
  50. K

    Trajectory of raindrop with horizontal wind

    Hi all, This question just occurred to me: Whether a falling raindrop in presence of a uniform horizontal wind (ideally speaking) has a curve trajectory or a straight line? Assuming the wind force is constant, the velocity of the raindrop in horizontal direction will keep on changing since there...
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