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At 90° off the wind, a craft is on a beam reach. The point of sail between beating and a beam reach is called a close reach. At 135° off the wind, a craft is on a broad reach. At 180° off the wind (sailing in the same direction as the wind), a craft is running downwind. [1]
This reduces the shadow zone, but causes errors in distance and height measuring. In practice, to find D h {\displaystyle D_{h}} , one must be using a value of 8.5·10 3 km for the effective Earth's radius R e {\displaystyle R_{e}} (4/3 of it), instead of the real one.
Proposition 17a in al-Tusi's medieval Arabic version of the book On Sizes states that the ratio of the distance of the vertex of the shadow cone from the center of the Moon (when the Moon is on the axis [that is, at the middle of an eclipse] of the cone containing the Earth and the Sun) to the distance of the center of the Moon from the center ...
The solar azimuth angle is the azimuth (horizontal angle with respect to north) of the Sun's position. [1] [2] [3] This horizontal coordinate defines the Sun's relative direction along the local horizon, whereas the solar zenith angle (or its complementary angle solar elevation) defines the Sun's apparent altitude.
Scattering by particulates impairs visibility much more readily. Visibility is reduced by significant scattering from particles between an observer and a distant object. The particles scatter light from the sun and the rest of the sky through the line of sight of the observer, thereby decreasing the contrast between the object and the ...
The shadow of Earth on the Moon during a lunar eclipse is always a dark circle that moves from one side of the Moon to the other (partially grazing it during a partial eclipse). The only shape that casts a round shadow no matter which direction it is pointed is a sphere, and the ancient Greeks deduced that this must mean Earth is spherical. [8]
The law currently requires wind turbines to be a distance at least equal to the height of the structure away from property lines. However bills 28, 29 and 30 all look to increase that amount ...
In order to use the instrument, the navigator would place the shadow vane at a location anticipating the altitude of the sun. Holding the instrument in front of him, with the sun at his back, he holds the instrument so that the shadow cast by the shadow vane falls on the horizon vane at the side of the slit.