- A blacklight, also called a UV-A light, Wood’s lamp, or ultraviolet light, is a lamp that emits long-wave (UV-A) ultraviolet light and very little visible light. One type of lamp has a violet filter material, either on the bulb or in a separate glass filter in the lamp housing, which blocks most visible light and allows through UV, so the lamp has a dim violet glow when operating. Blacklight lamps which have this filter have a lighting industry designation that includes the letters “BLB”. This stands for “blacklight blue”. A second type of lamp produces ultraviolet but does not have the filter material, so it produces more visible light and has a blue color when operating. These tubes are made for use in “bug zapper” insect traps, and are identified by the industry designation “BL”. This stands for “blacklight”.
- Great Slave Lake (Wikipedia)
Great Slave Lake is the second-largest lake in the Northwest Territories of Canada (after Great Bear Lake), the deepest lake in North America at 614 m (2,014 ft), and the tenth-largest lake in the world by area. It is 469 km (291 mi) long and 20 to 203 km (12 to 126 mi) wide. It covers an area of 27,200 km2 (10,500 sq mi) in the southern part of the territory. Its given volume ranges from 1,070 km3 (260 cu mi) to 1,580 km3 (380 cu mi) and up to 2,088 km3 (501 cu mi) making it the 10th or 12th largest by volume.