Recently in my purple science class we learned about air pressure and global winds. Air pressure is based on the temperature the water vapor and the elevation. The higher the altitude the lower the density and the lower the altitude the higher the density. "High" density is more dense and has fair weather. Also it is more dry than areas with a lower density. "Low" density has stormy weather and is less dense. Along with that the ground that has a less dense air has a moist or wetter ground.
Global winds are a very important part of our weather. The corolis effect is when the northern hemisphere winds cuve right and the southern winds curve left. Trade winds are about 30 degrees north and south of the equater. This is when the warm air rises from the equator cools and begins to sink. Horse latitudes are 30 degrees north and south. They are called the horse latitudes because they used to throw horses off of the boats because they were too heavy t carry along their trip. Prevaling westerlies are 40- 60 degrees. They are located in the latitude of both hemispheres. They are also very strong winds. Polar Easterlies are 50- 60 degrees latitude. The cold air is deflected by the corolis effect.
Air pressure is measured by a barometer. Two of the most common are the mercury barometer and the aneroid barometer. The aneroid barometer uses an aneroid cell to measure pressure. On the other hand, a mercury barometer is a tube with a reservoir of mercury at one end.
I got my information from:
http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/circulation/air_pressure_p_1.html
