GEOGRAPHY EXAM 2
What is a Warm Front
The slope of a warm front is not as steep as the slope of a cold front.
Describe the pattern of vertical air movement within a cyclone and within an anticyclone.
Air descends in anticyclones and rises in cyclones.
What generally happens to atmospheric pressure with increasing altitude?
Atmospheric pressure decreases because the further away you go from Earth and it's gravitational pull, the fewer gas molecules are present in the atmosphere.
What generally happens to atmospheric pressure with increasing altitude?
Atmospheric pressure decreases with increasing altitude. The reason for this is that lower altitudes, the gas molecules present in the atmospheric are packed more densely together than at higher altitudes. There are more molecular collisions.
When the temperature of the Earth's atmosphere increases
The air around the Earth expands and its volume increases, this in turn decrease the air density. The decreases in air density results in lowering the atmospheric pressure Thus the increase in air temperature generally results into the decrease in atmospheric pressure causes by the decrease in air density.
Describe the relationship between the "steepness" of a pressure gradient and the speed of the wind along that pressure gradient. Describe the general wind speed associated with a gentle (gradual) pressure gradient and a steep (abrupt) pressure gradient.
Wind speed is determined by the pressure gradient which is indicated by the spacing of isobars, which determines the steepness. If the gradient is steep the air accelerates quickly if the gradient is gentle, the acceleration is slow.
What is a cyclone? what is an anticyclone?
cyclone: low pressure centers for wind flow anticyclone: high pressure centers for wind flow
Describe the following terms: isobar, barometer, millibar
isobar: isolines of equal pressure. barometer: an instrument to measure atmospheric pressure millibar: an expression of force per surface area
what is a front
it is a boundary that exists between two different types of air masses. They contain aure with varying properties like density, humidity, wind patters, and stability.
What is a Cold Front
A cold front is more dense and easily displaces a warm front. It is more steep than a war front and the rapid lifting makes the arm are unstable. Therefore adiabatic cooling takes places and leads to the0 formation of cumulonimbus clouds. Incoming cold air mass prevails over a warm air mass.
Maritime polar (mP) air masses coming from Atlantic Ocean.
Are not as important because they are not able to affect much of North America, except mid-Atlantic coastal region due to prevailing westerly atmospheric circulation.
what causes a dynamic high near the surface? A dynamic low?
Dynamic highs are caused by strongly descending air. Dynamic lows are caused by strongly rising air.
How and why are friction layer (surface) winds different from upper-atmosphere geostrophic winds?
Geostrophic winds flow parallel to the isobars. Friction layer winds cross the isobars at angles between 0 and 90 degrees. In the upper atmosphere gas molecules do not come into contacts as frequent. This minimizes the air friction in the upper atmosphere so the winds move faster.
When referring to air pressure, what is a high, a low, a ridge, and a trough?
High: Pressure that is higher than surrounding areas low: pressure that is lower than surrounding areas ridge: an elongated area of relatively high pressure trough: an elongated area of relatively low pressure
Why are maritime polar masses form the Atlantic Ocean less important to the untied states than MP air masses from the Pacific OCean
Maritime polar (mP) air masses coming from the Pacific Ocean are full of moisture and bring heavy precipitation in the mountainous coastal region of United Stats, and hence these are very important
what parts of the world are most affected by midlatitude cylones
Mid Latitude cyclones typically affect latitudes between 30 and 60 degrees. Its a major disturbance in westerlies faster in winter Counter clockwise in northern hemisphere
"explain the process of occlusion. Why does an occluded front usually indicate the "death" of a midlatitude cyclone"
Occluded fronts are causes by more rapid movement of cold fronts as compared to warm fronts in a midlatitude cyclone. A midlatitude cyclone is a cold front that is preceded by a warm front, the cold front overtakes it. This creas temperature inversions, the midlatitude cyclone creates aloft and atmospheric stability is reached.
Explain how atmospheric pressure is related to air density and air temperature
The denser the gas, the more pressure it exerts. Because the density is higher, there are more collisions and therefore higher pressures. The higher the temperature, the more pressure is exerted. As the temperature rises, the molecules speed up which cause more collisions, exerting a higher pressure.
Why don't winds simply flow down a pressure gradient?
The frictional force present in the air is greatest near the Earth surface, because the density of air is greatest at low altitudes. The frictional drag of air slows the wind movement and the balance between the pressure gradient and Coriolis Effect is disturbed. The air flows between 0-90 degrees.
What causes a thermal high near the surface? a thermal low?
Thermal highs are caused by very cold surface conditions. Thermal lows are caused by very warm surface conditions.
What is the reason for the difference in wind flow patterns in the Northern Hemisphere and the Southern Hemisphere?
They flow in opposite directions.
What is the pattern of wind flow in the Northern Hemisphere around a surface high? a surface low? an upper atmosphere high? an upper atmosphere low?
surface high: a divergent clockwise flow surface low: converging counterclockwise flow upper atmosphere high: move clockwise in a geostrophic manner parallel to the isobars. upper atmosphere low: moves counterclockwise in a geostrophic pattern parallel to the isobars.
What is meant by a pressure gradient?
the horizontal rate of pressure change with distance. It represents the steepness or abruptness of the pressure change over a distance. If the pressure gradient is gentle, the air speed is generally low. If the pressure gradient is steep the air is generally fast. Air well began to move from high pressure to low pressure.
What three factors influence the direction of wind flow?
the pressure gradient, the Coriolis effect, and friction
