Albedo distribution of solar radiation reaching the Earth's surface. These factors vary with atmospheric composition, geographic location and time (see position of the Sun). While bi-hemispherical reflectance is calculated for a single angle of incidence (i.e., for a given position of the Sun), albedo is the directional integration of reflectance over all solar angles in a given period. The temporal resolution may range from seconds (as obtained from flux measurements) to daily, monthly, or annual averages. Unless given for a specific wavelength (spectral albedo), albedo refers to the entire spectrum of solar radiation. Due to measurement constraints, it is often given
Surface-to-air missile than aircraft. Virtually all surface warships can be armed with SAMs, and naval SAMs are a necessity for all front-line surface warships. Some warship types specialize in anti-air warfare e.g. "Ticonderoga"-class cruisers equipped with the Aegis combat system or "Kirov" class cruisers with the S-300PMU "Favorite" missile system. Modern Warships may carry all three types (from long-range to short-range) of SAMs as a part of their multi-layered air defence. SAM systems generally fall into two broad groups based on their guidance systems, those using radar and those using some other means. Longer range missiles generally use radar for early detection