Friday, 11 May 2012


Amaryllidaceae are a family of herbaceous, perennial and bulbous flowering plants included in the monocot order Asparagales. The family takes its name from the genus Amaryllis, hence the common name of the Amaryllis family.

There have been widely differing views as to the limits of the family. The most recent APG classification (APG III takes a broad view of the Amaryllidaceae, which then has three subfamilies, the Agapanthoideae (the old Agapanthaceae family), the Allioideae (the old Alliaceae family) and the Amaryllidoideae (the old Amaryllidaceae family). With this definition, the family includes about 75 genera and 1600 species.
Plants have rather fleshy and two-ranked leaves and flowers typically arranged in umbels at the apex of leafless flowering stems, or scapes. The Agapanthoideae have superior ovaries, as do the Allioideae, the onion subfamily. The Allioideae produce allyl sulfide compounds which give them their characteristic smell. The Amaryllidoideae have inferior ovaries.

Friday, 24 February 2012


Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture, called the Absolute humidity. In everyday usage, it commonly refers to relative humidity, expressed as a percent in weather forecasts and on household humidistats; it is so called because it measures the current absolute humidity relative to the maximum. Specific humidity is a ratio of the water vapor content of the mixture to the total air content (on a mass basis). The water vapor content of the mixture can be measured either as mass per volume or as a partial pressure, depending on the usage.

In meteorology, humidity indicates the likelihood of precipitation, dew, or fog. High relative humidity reduces the effectiveness of sweating in cooling the body by reducing the rate of evaporation of moisture from the skin. This effect is calculated in a heat index table, used during summer weather.