Roque de los Muchachos Observatory (ORM) at La Palma (Canary Islands) is one of the two top sites selected for hosting the future European Large Telescope (ELT) (http://www.eso.org/projects/e-elt/), the other being Paranal (in Chile). Meteorological and seeing conditions are crucial for the site selection. New concepts related to geophysical properties (seismicity and microsismicity), local climate variability, the presence of aerosols, atmospheric conditions related to the optical turbulence (tropospheric and ground wind regimes) have recently been introduced for selecting sites for a new generation of Extremely Large Telescopes (Munoz-Tunon 2002, Munoz-Tunon et al. 2003 a, 2003 b; Varela et al., 2002; Varela & Munoz-Tunon, 2004; Varela et al., 2004 a, 2004 b) and also for telescope design and feasibility studies for adaptive optics. Wind speed at 200 mbar is one of the key parameters proposed for characterizing atmospheric turbulence above the Observatory (Sarazin & Tokovinin, 2002, Garcia-Lorenzo et al., 2005). A lower average 200 mbar wind speed is obtained at the ORM in comparison with other astronomical sites; furthermore, the ORM ranks first in in suitability for adaptive optics suitability (Garcia-Lorenzo et al., 2005). The usefulness of this value might be conditional on the continuity of the wind value and wind direction from the upper troposphere to the ground level. With this motivation we are undertaking a study of tropospheric and ground winds at several observing sites.