wind

*Development of Wind

Wind usually refers to the movement of air parallel to the earth's surface.

The driving forces of winds in the lowest few hundred feet of the atmosphere are pressure differences caused by unequal heating of the air. The direction is also affected by the Coriolis force. Normally, wind requires several hours to develop.

*Velocity Profile

The roughness of the earth's surface causes the surface wind speed to be much less than the wind speed at higher levels. Velocity profiles have been determined by fitting curves to observed mind speeds at several levels, is described by a power law of the form:

Vh = Vr*(h/hr)^k

where Vh is the mean wind speed at height h above the ground, Vr is the mean speed at the reference height h (10 metres or about 30 feet is internationally recommended as the standard), above the ground, k is the exponent for the best-fitting curve.

*Turbulence in Surface Winds

Superimposed on the mean speed are gusts and lulls. These gusts have a random distribution over a wide range of frequencies and amplitudes, both in time and space.

*Design Wind Speeds

The basic design wind load in the National Building Code of Canada is the velocity pressure of a wind lasting for a few seconds that will be exceeded on the average once in 30 years.

Wind loads have become particularly significant because of the increasing number of high-rise buildings. Other factors have also contributed to the importance of wind in design: light-weight low-slope roofs, curtain wall construction and the appearance of special structures having "aerodynamic shapes."

Wind loads have become particularly significant because of the increasing number of high-rise buildings. Other factors have also contributed to the importance of wind in design: light-weight low-slope roofs, curtain wall construction and the appearance of special structures having "aerodynamic shapes."

Tidbits

National Wind Technology Center

"research facility managed by NREL.. researchers work with members of the wind energy industry to advance wind power technologies that lower the cost of wind energy... wind turbine designs."




RCI-Mercury - Resource for Roofing and Waterproofing Information

Excellent "online roofing and waterproofing document resource. " on Coatings Codes, Associations, Standards, Wood Expansion Joints, etc.; ...technical journal of the Roof Consultants Institute.




Weather data viewer

"Design conditions were determined for 509 US, 134 Canadian, 339 European, 293 Asian and 169 other worldwide locations for a total of 1444 locations. Thirty-three years of hourly weather data were used for approximately 1/2 of the US and all of the Canadian locations. Twelve years of data were used for the other locations. "




WMO - World Meteorological Organization

"... coordinates global scientific activity to allow increasingly prompt and accurate weather information and other services for public, private and commercial use, including international airline and shipping industries."

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Chaotic fluctuation in natural wind and its application to thermal amenity, by Hara, T., Shimizu, M., Iguchi, K. and Odagiri, G., 1997

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Damage, shelter, and other performance issues for buildings in high wind regions, by Rosowsky, D. V. and Schiff, S. D., 2002

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Inaccuracies in standard meteorological low-speed wind data, by Levermore, G., C. Sanders, J. Dewsbury, A. Gadian and P. Laycock, 2001

wind and hurican on roof

Keeping roofs on and working, by Paroli, R. and Baskaran, A., 1996

windstorm

Lessons learned from failures of the building envelope in windstorms, by Minor, J. E., 2005

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O86.1-94 Engineering Design in Wood (Limit States Design), by CSA, 1994

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Overview of turbulence models applied in CWE-1997, by Murakami, S., 1998

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Pedestrian wind environment around buildings: literature review and practical examples, by Blocken, B., Carmeliet, J., 2004

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Review of the need for a large-scale test facility for research on the effects of extreme winds on structures, by Commission on Engineering and Technical Systems (CETS), 1999

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Ventilation through building walls - wind tunnel studies, by Broasa, P., 1996

wind and air pressure

Wind and Air Pressures on the Building Envelope, by Ganguli, U., 1986

wind daamage of wood house

Wind damage to wood frame houses: problems, solutions, and research needs, by Liu, H., Saffir, H.S., and Sparks, P.R, 1989

simple description

Wind on Buildings, by Dalgliesh, W. A. and D. W. Boyd, 1962

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Wind resistance of light-frame structures, by Wolfe, R. W., 1998