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.
Measure the width of the existing fireplace. 3. Using the T-square, transfer the dimensions onto the MDF. 4. To create the crown and arch of the top of the mantel, you will need to decide how far to extend the width and then mark the MDF. This measurement needs to be equal on both sides. 5. Decide the height of the crown and mark it on the MDF. 6.