Each tonsil consists of a network of crypts (pits) that store cells used to fight infection. The tonsils contain B cells, a type of white blood cell that fights infections. They also produce antibodies against polio, streptococcal pneumonia, influenza, and numerous other infections.
Global Warming: What's Up With The Weather? is a DVD presentation of the television special by NOVA and Frontline dealing with questions raised about modern climate change.
(wÄ'Ér) The state of the atmosphere at a particular time and place. Weather is described in terms of variable conditions such as temperature, humidity, wind velocity, precipitation, and barometric pressure. Weather on Earth occurs primarily in the troposphere, or lower atmosphere, and is driven by energy from the Sun and the rotation of the Earth. The average weather conditions of a region over time are used to define a region's climate.