Points to Remember. 1  Marijuana refers to the dried leaves, flowers, stems, and seeds from the hemp plant, Cannabis sativa. 2  The plant contains the mind-altering chemical delta-9-tetrahydrocannabinol (THC) and other related compounds. 3  People use marijuana by smoking, eating, drinking, and inhaling it.
A cold front is symbolized on a weather map as a line with triangles. The triangles can be thought of as icicles. Cold fronts are often coloured blue. The presence of a cold front means that cold air is advancing and pushing underneath warmer air.
Air masses bring variety of weather. Six basic types of air masses affect the weather of the British Isles. They can bring anything from tropical warm and humid days to arctic cold depending on the type of air mass. Fronts form the boundaries of air masses with differing properties. The most severe weather usually occurs when dry-cold continental polar air clashes with warm-humid maritime tropical air.