The lowest part of the troposphere, where friction with the Earth's surface influences air flow, is the planetary boundary layer. This layer is typically a few hundred meters to 2 km (1.2 mi) deep depending on the landform and time of day.he troposphere is the lowest portion of Earth's atmosphere. It contains approximately 75% of the atmosphere 's mass and 99% of its water vapor and aerosols.
Bushnell is a city in Sumter County, Florida, United States. The population was 2,050 at the 2000 census. According to the U.S Census estimates of 2005, the city had a population of 2,119. It is the county seat of Sumter County.
Casselberry is a city in Seminole County, Florida, United States. The population was 22,629 at the 2000 census. According to the U.S Census estimates of 2009, the city had a population of 24,792. It is usually considered a suburb in the OrlandoâKissimmee-Sanford Metropolitan Statistical Area. Casselberry is located at 28Â°39â²37â³N 81Â°19â²24â³W / 28.660275Â°N 81.323264Â°W / 28.660275; -81.323264. According to the United States Census Bureau, the city has a total area of 7.1 square miles (18.4 kmÂ²).