Port-de-Goulée

A port is a location on a coast or shore containing one or more harbors where ships can dock and transfer people or cargo to or from land. Port locations are selected to optimize access to land and navigable water, for commercial demand, and for shelter from wind and waves. Ports with deeper water are rarer, but can handle larger, more economical ships. Since ports throughout history handled every kind of traffic, support and storage facilities vary widely, may extend for miles, and dominate the local economy. Some ports have an important military role.

A harbor or harbour (see spelling differences), or haven, is a body of water where ships, boats, and barges can seek shelter from stormy weather, or else are stored for future use. Harbors can be natural or artificial. An artificial harbor has deliberately constructed breakwaters, sea walls, or jettys, or otherwise, they could have been constructed by dredging, and these require maintenance by further periodic dredging. An example of the former kind is at Long Beach Harbor, California, and an example of the latter kind is San Diego Harbor, California, which was, under natural conditions, too shallow for modern merchant ships and warships.

In contrast, a natural harbor is surrounded on several sides by prominences of land. An example of this kind of harbor is San Francisco Bay, California.

Harbors and ports are often confused with each other. A port is a facility for loading and unloading vessels; ports are usually located in harbors.

In meteorology, a cloud is a visible mass of liquid droplets or frozen crystals made of water or various chemicals suspended in the atmosphere above the surface of a planetary body. These suspended particles are also known as aerosols. Clouds in Earth's atmosphere are studied in the cloud physics branch of meteorology. Two processes, possibly acting together, can lead to air becoming saturated; cooling the air or adding water vapor to the air. In general, precipitation will fall to the surface; an exception is virga, which evaporates before reaching the surface.

The international cloud classification system is based on the fact clouds can show free-convective upward growth like cumulus, appear in non-convective layered sheets such as stratus, or take the form of thin fibrous wisps, as in the case of cirrus. Prefixes are used in connection with clouds: strato- for low clouds with limited convection that form mostly in layers, nimbo- for thick layered clouds that can produce moderate to heavy precipitation, alto- for middle clouds, and cirro- for high clouds. Whether or not a cloud is low, middle, or high level depends on how far above the ground its base forms. Cloud types with significant vertical extent can form in the low or middle altitude ranges depending on the moisture content of the air. Clouds in the troposphere have Latin names due to the popular adaptation of Luke Howard's cloud categorization system, which began to spread in popularity during December 1802. Synoptic surface weather observations use code numbers to record and report the types of tropospheric cloud visible at each scheduled observation time based on the height and physical appearance of the clouds.

Perspective, in context of vision and visual perception, is the way in which objects appear to the eye based on their spatial attributes; or their dimensions and the position of the eye relative to the objects. There are two main meanings of the term: linear perspective and aerial perspective.

The development of new forms of geometric projection in the construction of perspective corresponds with the invention of novel pictorial art forms of visual representation in the Italian Renaissance, since the fourteenth century and up till the end of the sixteenth century, and specifically within the circles of architectural and artistic experimentation and design. Treatises were composed on perspective by eminent theorists of art and architecture, including figures like Leon Battista Alberti, Lorenzo Ghiberti, and Piero della Francesca, aided also by experimental uses of optical devices through the installations of Filippo Brunelleschi. The investigations and writings of these Renaissance theorists of architecture and visual art were informed by the studies in classical optics of thirteenth-century Franciscan perspectivists like Roger Bacon, John Peckham, and Witelo, who all were directly inspired and influenced by the translation into Latin from Arabic of the Book of Optics (known in Latinate renditions as Perspectiva, and in Arabic as Kitab al-manazir) of the eleventh-century Arab polymath and optician, Alhazen (Ibn al-Haytham).