Its very dificult

Hi Hengameh,

What do you mean by heavy materials?

Normally air density, at any one point and one time, depends on its temperature and pressure at that particular point and time.

So, if you have the measurement of temperature and pressure, the n you can calculate the density. (density = Pressure/(Temperature X universal gas constant)).

I hope this clears thing s with you.

Wan

Hi Wan and Mohsen Sepahi,

Thanks. This is related to a part  of  a  study in thisbook 

https://www.morebooks.de/store/bookprice_offer/show?token=4fa44ea9de8d9164be337b44caa06abed5afbc3f&auth_token=d3d3LnNjaG9sYXJzLXByZXNzLmNvbTpmYjdkMTE5ZGQyYTg3Nzk1MDBlNGFhZjc0ZDBjY2RlYQ==&locale=gb

I will be pleased to read your new comments after reading the book.

Hi Hengameh,

I hope you have found your answer; but, here is my short answer:

Density is estimated as a function of elevation, Z, and temperature, T. Attached is a wind assessment paper that provides enough info about this relation. Please check page 4, equations 17 and 18 to see this function. These equations are a more complete form of the function that Wan is written above.

Please let me know if you had further questions.

Conference Paper An Assessment on the Wind Energy Potential and Possible Solu...

Hi again everybody.

The paper that Navid brought  tp our attention is good. The equations given for the calculation of the air density is a liitle modified to take into account the altitude effect. Please note that the paper gives/assumes the sea level pressure value of the standard air. Hence the calculated air density that is obtained using the equations would still be the "standard" atmosphere values at height. Unless the pressure Po is the real measured value at "zero height".

What I am trying to say is, if you want the real air density value, you just need the static temperature and pressure (both real) at the point of interest, and you can calculate the air density (real). If you want the value at height, and you only have the temperature and pressure values at height zero, then you can use the equation in the paper.

Thank you.

Wan Zaidi 

Based on what Wan said, you can find the density (as a function of pressure and temperature) at certain height using the following equation:

Density(pressure,temperature)=(Ro)0 *(pressure/760)*(288.15/temperature)

(Ro)0= the density of dry air at Standard Temperature and Pressure...using ISA model, it is 1.225 [kg/m3] @ 288.15 K.

You can also find the temperature and pressure variations with height and find the density value at a desired height. 

Hi, thanks, Navid and Wan, your equations 17 and 18 are good reference for dry clean air  and equation 1 in book turbulence effect on wind-rain station. Moreover if you have studied poluted air and wet air, please let me know.

Hi. I have produced a simple rainfall-wind turbine blade in very small size. Have you read before about this and its test? Is there any center interested in it?