The troposphere contains 75 percent of atmosphere's mass-on an average day the weight of the molecules in the air is14.7 lb..(sq. in.)- and most of the atmosphere's water vapor.ater vapor plays a major role in regulating air temperature because it absorbs solar energy and thermal radiation from the planet's surface. The troposphere contains 99% of the water vapor in the atmosphere. Water vapor concentrations vary with latitudinal position(north to south).
Proper is different from typical or average. Average mantel height is about 54 above the hearth extension. Proper depends on the fireplace size, required clearances and the aesthetic desired, which can vary widely. These are both proper mantel heights: This one's about 48 high.
The size of your mantel is an important factor in determining the time, labor, and skill needed for installation. Whether your project includes a single mantel shelf or a full fireplace surround, the overall width of the piece or set can be a good indicator of the scope of the job. Installation rates average $287 for a 36â mantel, $344 for one 42â wide, $461 for a 48â mantel, and $587 for a 60â unit.