Weight of air
Depending on elevation, the air pressure
varies. This is because of the weight of the air that is exerting pressure on
earth. At higher elevation, there is less layer of air that is exerting pressure
so the atmospheric pressure is also less. At lower altitudes or at sea level,
more layer of air is exerting pressure so the atmospheric pressure is also
more. The sun’s energy has nothing to do with air pressure. The energy that the
Earth gets from the sun is more or less constant. The same with density of
nitrogen, and the earth’s magnetic field, they have nothing to do with air
pressure.
The stem is most likely made up of vascular tissues. The main vessels present on vascular tissue are the xylem and phloem. These two tissues work as pipes for the transport of water and nutrients inside the stem. Xylem transports water and some nutrients from the roots. The Phloem <span>transports the soluble organic compounds that were produced during </span>photosynthesis from the leaves, and in the case of the cactus photosynthesis happens on the actual stem,<span> to the rest of the plant.</span>
A scale shows the distances bewtween places on a map.
