You know I am in the UK
and us English live to talk about weather !!!

Today we have a rather unusual strong storm,
so you can guess what the news is all about

Anyway

It go me thinking ,
how much "power" / "energy" is there in the wind ?
and i did not know.

First thought was F=ma

A being acceleration,
so assumed wind hit something and stopped, that the "wind speed"
but that seemed very un realistic,

and then I came to the mass
and wondered, dry air wet air / rain, that must all affect the density , and thus the mass

Did a bit of googling,
but either very complex equations / measurements

or impossible un realistic,

As a related note,

my gazebo that is 3m by 3m, and had 40Kg of weights on it, is now in next doors garden,
may be one side failed then rest, but ..

So wondered,
in days of old,
sail ships, or even side of buildings, there must be tables some where of wind speed and how much energy they can impart

Any one got link to such ?

Ta

 

I can't help with equations but I do know that the force is large.
I have sailed a small dinghy and some small yachts and you need to pull in the sails against the wind. I was really surprised how hard that was even with a small dinghy sail.

 

Hello there You are looking for a chart involving wind velocity ,pressure, density & temperature as a function of space and time? Or perhaps an Psychrometric chart for standard atmospheric conditions.
The force acting directly on your gazebo would be difficult to calculate due to drag, turbulence, friction, dynamic pressure, kinetic energy-per unit volume.
What immediately came to mind is the Beaufort Wind Scale.
I'm definitely out of my comfort zone here.
Or perhaps you might look into wind power turbines.
I'm from California so not much weather haha. All I care about is going surfing in the morning and snowboarding at night.

 

Isn't it amazing just how many thing there are in the garden that have to be put under cover?

The force exerted by the wind must be the same as the aerodynamic drag force of a moving vehicle
\(
F=0.5 \rho v^2 C_d A
\)
where Cd is the coefficient of drag and a is the area.

The energy must just be the kinetic energy of the mass moving at the windspeed.

 

As a starting point, to get some feel for the force/energy involved, note that 1 cubic metre of (dry) air weighs about 1kg. So imagine umpteen kg of air being thrown at tens of m/sec at your gazebo.

 

As a starting point, to get some feel for the force/energy involved, note that 1 cubic metre of (dry) air weighs about 1kg. So imagine umpteen kg of air being thrown at tens of m/sec at your gazebo.

That's a good number to remember, thank you , 1kg dry air weight 1 kg.
Thanks .
It's just something I realised I did not have handle on. .


quick calculation

3m square gazebo, 9 square meters
70 MPH winds, is around 30 m per second

F=ma gives around 270 Kg of force,
thats explains the gazebo moving,

Ta

 

KE=1/2mV2 can be used calculate the energy transferred to the windmill based on initial wind speed and new wind speed (after it is slowed by the turbine blade). There is an "optimum" where energy is captured but you cannot capture it all (final airspeed =0) because you'd end up with a traffic jam of gridlocked air at the windmill and new incoming air will not reach the turbine.

There are some good calculations on Wikipedia and youtube. If I remember correctly, there is some equation that says the most you can get out is 30% with wind speeds over 20mph. The efficiency is less at lower wind speeds. That's why few areas are worthy of a windmill installation at current windmill prices and possible energy savings costs. Solar seems to be a better investment in most parts of the world and using wind/solar delivered from elsewhere is also smart for many areas that are dreary with little wind.

 

That's why few areas are worthy of a windmill installation at current windmill prices and possible energy savings costs. Solar seems to be a better investment in most parts of the world and using wind/solar delivered from elsewhere is also smart for many areas that are dreary with little wind.

I completely agree. Turbine prices have actually fallen, but tower prices have remained steady or increased. Turbulence will ruin most domestic wind projects because of the presence of a large brick object which spoils the airflow - i.e. a house! And Solar is much more reliable (unless the wind blows the panels off your roof)

 

There is an "optimum" where energy is captured but you cannot capture it all (final airspeed =0) because you'd end up with a traffic jam of gridlocked air at the windmill and new incoming air will not reach the turbine.

. . . and so-called "scientific journalists" say that this lack of efficiency is some sort of failing on the part of the wind-turbine designers.

 

Luckily,
I was not thinking of a windmill / turbine

It was just a though that I could not even do a best case F=ma.

As for windmills or as we now call them in the UK, turbines,
they use wings, to increase the efficiency,

As for boat,
my god daughters boat,
she sails by "sip puff"
across the atlantic
( scares the ^&*( out of me )

can and does go significantly faster than the wind ...

http://www.missisle.com/

 

Wind turbines and windmills are distinct things. A windmill is literally a mill powered by the wind. Whereas a wind turbine is literally a power generator powered by the wind.

Windmills are for making flour and wind turbines are for mining crypto.

 

When you talk about extremes in the United states we deal with tornadoes regularly. Some of the things they do it is downright amazing and scary. I remember reading a hurricane has the power of several atomic bombs. Like most statements like this I cannot prove it though.