Vapor

In physics a vapor (American English spelling) or vapour (British) is a substance in the gas phase at a temperature lower than its critical point, which means that the vapor can be condensed to a liquid by increasing the pressure on it without reducing the temperature. A vapor is a different substance than an aerosol. An aerosol is a suspension of tiny particles of liquid, solid or both within a gas.

For example, water has a critical temperature of 374 °C (647 K), which is the highest temperature at which liquid water can exist. In the atmosphere at ordinary temperatures, therefore, gaseous water (known as water vapor) will condense into a liquid if its partial pressure is increased sufficiently.

A vapor may co-exist with a liquid (or a solid). When this is true, the two phases will be in equilibrium, and the gas-partial pressure will be equal to the equilibrium vapor pressure of the liquid (or solid).

Properties

Vapor refers to a gas phase at a temperature where the same substance can also exist in the liquid or solid state, below the critical temperature of the substance. (For example, water has a critical temperature of 374 °C (647 K), which is the highest temperature at which liquid water can exist.) If the vapor is in contact with a liquid or solid phase, the two phases will be in a state of equilibrium. The term gas refers to a compressible fluid phase. Fixed gases are gases for which no liquid or solid can form at the temperature of the gas, such as air at typical ambient temperatures. A liquid or solid does not have to boil to release a vapor.

Vine

A vine (Latin vīnea "grapevine", "vineyard", from vīnum "wine") in the narrowest sense is the grapevine (Vitis), but more generally it can refer to any plant with a growth habit of trailing or scandent (that is, climbing) stems or runners. The word also can refer to such stems or runners themselves, for instance when used in wicker work.

In the United Kingdom, the term "vine" applies almost exclusively to the grapevine. The term "climber" is used for all climbing plants.

Growth forms

Certain plants always grow as vines, while a few grow as vines only part of the time. For instance, poison ivy and bittersweet can grow as low shrubs when support is not available, but will become vines when support is available.

A vine displays a growth form based on long stems. This has two purposes. A vine may use rock exposures, other plants, or other supports for growth rather than investing energy in a lot of supportive tissue, enabling the plant to reach sunlight with a minimum investment of energy. This has been a highly successful growth form for plants such as kudzu and Japanese honeysuckle, both of which are invasive exotics in parts of North America. There are some tropical vines that develop skototropism, and grow away from the light, a type of negative phototropism. Growth away from light allows the vine to reach a tree trunk, which it can then climb to brighter regions.