Solar zenith angle minutes of arc, which is less than the apparent angular radius of the sun. The formula also neglects the effect of atmospheric refraction. Sunset and sunrise occur (approximately) when the zenith angle is 90°, where the hour angle "h" satisfies Precise times of sunset and sunrise occur when the upper limb of the Sun appears, as refracted by the atmosphere, to be on the horizon. A weighted daily average zenith angle, used in computing the local albedo of the Earth, is given by where "Q" is the instantaneous insolation. For example, the solar elevation angle is : An exact calculation
Less than truckload shipping Less than truckload shipping Less than truckload shipping or less than load (LTL) is the transportation of relatively small freight. The alternatives to LTL carriers are parcel carriers or full truckload carriers. Parcel carriers usually handle small packages and freight that can be broken down into units less than . Full truckload carriers move freight that is loaded into a semi-trailer. Semi-trailers are typically between and require a substantial amount of freight to make such transportation economical. There are several different perspectives as to what is actually considered LTL. Full Truck Load carriers can put anywhere from 2 to 6