Atmosphere in Motion (Earth Science Class) - Essay Example

List units and instruments that measure air pressure - Mercury barometer, used to measure air pressure, is made of a glass tube from which the air has been removed. The empty tube is placed in mercury dish. The air in the atmosphere pushes against the mercury in the dish, causing the mercury to rise in the barometer. - Aneroid barometer, used also to measure air pressure, is made of a flexible metal bellow, from which the air has been removed and then the bellow sealed. The higher atmospheric pressure causes the bellow to contract and expand; the measurement of air pressure is then recorded onto a rotating cylinder of paper.

The advantage of using the aneroid barometer is that the readings are more accurate and that a week’s worth of data is recorded with each cylinder. 2- Explain how the pressure gradient force, Coriolis Effect, and friction affect wind Coriolis Effect: Wind moves to the right of the direction of the body motion for counterclockwise rotation of the frame of reference, or to the left for a clockwise rotation; this is called the Coriolis Effect. The pressure gradient force and the Coriolis Effect work together to channel the air flow.

The pressure gradient force causes air to start moving across the isobars; as soon as the air starts to move, the Coriolis Effect acts at right angles to this motion. Friction is an additional factor that has a significant effect on the wind, changing both its velocity and its direction. Friction causes wind to decrease, thus decelerating the Coriolis Effect. This makes the wind corkscrew away from the high pressure centers and into the low pressure centers in the Northern Hemisphere. It has the contrary effect in the Southern Hemisphere.

3- Discuss the movements of air and weather patterns associated with cyclones and anticyclones. A wind in a cyclone blows counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Winds in an anticyclone blow just the opposite; the isobars are far apart, resulting in lighter winds. In cyclones, air closest to the ground is forced inward toward the center of the cyclone, where the air pressure is lowest. It then begins to rise upward, expanding and cooling in the process.

These isobars are closer together, which creates a steeper gradient pattern, thus higher, stronger winds. Cooling increases humidity in the rising air, which produces increased clouds and elevated humidity in the cyclonic winds. 4- Discuss global patterns of pressure and wind? There are four global pressure zones: high, low, high, and low from poles to equator. - Three global wind belts: polar easterlies, westerlies (subpolar jet streams in the upper atmosphere and longwaves), and trade winds (SE and NE) - Pressure zones and wind belts shift north and south with the seasons - Land and sea breezes, winter and summer monsoons.

Land and sea breezes are caused by the air pressure in differing temperatures. The land breezes flow from the cooler land towards the warming sea in the daylight, the sea breezes flow in the opposite direction from the cooler sea towards the warmer land mass at night. A monsoon is a major wind system that seasonally changes its direction, blowing six months from the northeast, then six months from the southwest. The wind blows from the cold toward the warmth, therefore, from the sea toward the land in the summer and the land towards the sea in the winter.

Summer monsoons are usually wet and winter monsoons are dry. - Subtropical high pressure cells drive oceanic circulation; warm and cold currents, “thermohaline” circulation, is a conveyor belt “overturning” circulation where the warm water flows towards the poles at the upper surface, then is mixed with cold water that sinks and flows towards the equator. 5- Explain atmospheric circulation in the mid-latitudes Atmospheric circulation is the movement of air at all levels of the atmosphere by which heat is distributed over the planet.

The power house behind atmospheric circulation is solar energy, which heats the atmosphere with different intensities at the equator, the middle latitudes, and the poles. The middle latitudes are affected by the Ferrell cells, also known as prevailing westerlies, the trade wind air that has traveled towards the poles instead of the equator. This air flows over the mid-latitudes from the 30 to the 60 degrees. 6- Discuss various local winds (e.g., sea and land breezes) Local winds blow over a smaller area than global winds and have a shorter duration.

Hot winds are caused by anticyclones over arid areas; cold winds originate over mountains and snowy areas and can be associated with cold fronts. Sea and land breezes are winds that flow with the temperature changes. Sea breezes move from the cold land to the warm sea (daylight), land breezes move from the cooled sea to the warmed land (nightfall). 7- Discuss wind measurements and instruments. The device to measure the wind speed (velocity) or air pressure is called the anemometer. There are two classes of the anemometer; one is used to determine the wind’s speed and the other one is used to determine the wind’s pressure.

The most common anemometers are the cup version and the propeller style. Other common instruments are weather vanes, used to establish wind direction, and windsocks, utilized to measure wind speed and direction.