The zenith angle is the angle between the sun and the vertical. The zenith angle is similar to the elevation angle but it is measured from the vertical rather than from the horizontal, thus making the zenith angle = 90° – elevation.

90°

Zenith, in astronomy terms, is the point in the sky directly overhead. According to astronomers, there is no zenith for a Sun’s position but to any observer, the Sun has reached its zenith if it is directly overhead. The angular distance from the zenith to any celestial body, in space, is called the zenith distance.

The angle between a straight line from a point on the earth’s surface to the satellite and a line from the same point on the earth’s surface that is perpendicular to the earth’s surface at that point (the zenith point).

Zenith Angle

• Reflectance.
• Wavelength.
• Leaf Area Index.
• Albedo.
• Irradiance.
• Radiance.
• Aerosol.
• Altitude.

The azimuth angle is like a compass direction with North = 0° and South = 180°. Other authors use a variety of slightly different definitions (i.e., angles of ± 180° and South = 0°).

60°

Solar radiations So in observing the sun from earth, the solar hour angle is an expression of time, expressed in angular measurement, usually degrees, from the solar noon. For example, at 10:30 a.m. local apparent time the hour angle is −22.5° (15° per hour times 1.5 hours before noon).

The solar azimuth is the angle of the direction of the sun measured clockwise north from the horizon. The solar zenith is the angle measured from the local zenith and the line of sight of the sun.

Zenith, point on the celestial sphere directly above an observer on the Earth. The point 180° opposite the zenith, directly underfoot, is the nadir.

The zenith angle (Z) is “the number of degrees between a site location and the declination of the Sun.” Given that we can’t have a negative Z, just make it a positive number. It still is by definition “the number of degrees between a site location and the declination of the Sun.”

The solar azimuth ψ is the angle at the local zenith between the plane of the observer’s meridian and the plane of a great circle passing through the zenith and the sun. It is measured east positive, west negative (south zero) and thus varies between 0° and ± 180°.

Highest mountain on Earth?

• Mount Everest’s peak is the highest altitude above mean sea level at 29,029 feet [8,848 meters].
• Mount Chimborazo’s peak is the furthest point on Earth from Earth’s center.
• Mauna Kea is the tallest mountain from base to peak at more than 33,500 feet [10,210 meters].

Answer: The angle between the hour and minute hand at 3 PM is 90°

Solar altitude angle, α The solar altitude angle is the angle between the sun’s rays and a horizontal plane, as shown in Figure 2.8. It is related to the solar zenith angle, Φ, which is the angle between the sun’s rays and the vertical.

True solar time (TST, also known as local apparent time or apparent solar time) True solar time is determined by the difference between the Greenwich Hour Angle of a location (which is fixed) and that of the sun, which changes by approximately15° an hour as it traverses the sky.

Two types of solar times are apparent solar time (sundial time) and mean solar time (clock time).

around 24 hours

Solar time, time measured by Earth’s rotation relative to the Sun. Apparent solar time is that measured by direct observation of the Sun or by a sundial.

In terms of solar time, noon is the moment when the Sun crosses the local meridian and reaches its highest position in the sky, except at the poles. This version of noon is also called solar noon or high noon.

Modern timekeeping defines a day as the sum of 24 hours—but that is not entirely correct. The Earth’s rotation is not constant, so in terms of solar time, most days are a little longer or shorter than that. The Moon is—very gradually—slowing the Earth’s rotation because of friction produced by tides.

Although a simple definition of a day is the time it takes for a planet, satellite or other celestial body to complete one rotation about its axis, two alternative definitions exist. The speed chosen is the average speed of the Sun’s ecliptic motion, leading to a mean solar day of 24 hours. …