first 10 Flashcards
Identify examples of instruments used to measure and/or record wind characteristics.
anenometer - measures wind
radiosondes (weather balloons) - measure pressure, altitude, temp, relative humidity, wind speed and direction
tethersonde - tethered weather balloon
doppler radar - measures upper-level winds
Identify the general characteristics associated with winds and pressure gradients.
Wind is caused by differences in atmospheric pressure between locations, moving from high pressure areas to low pressure ones, and this is known as pressure gradient force.
Pressure gradients are depicted on maps with isobars - the farther apart, the weaker the gradient and the weaker the winds.
Understand the relationship between temperature and pressure and be able to determine the impact that warming or cooling of an air mass/column has on its pressure near the surface and aloft in the atmosphere.
Pressure gradients are the result of uneven heating of the atmosphere.
Differences in temperature between regions can produce changes in pressure both at the surface and aloft.
As air warms, it expands, and pressure at the surface decreases while pressure aloft increases.
As air cools, it contracts, surface pressure increases while pressure aloft decreases.
Identify the general characteristics associated within land and sea breezes. Focus attention on the forces that give rise to differences in pressure and how this translates into changing wind directions.
Land heats during day, air above it expands and rises and creates lower pressure conditions at surface.
Land heats up and cools down quicker than water, higher pressure at night as it cools. Air moves from higher pressure areas to lower pressure ones - wind from ocean to land during day, and from land to sea during night.
Identify examples of other types of local winds and the general characteristics of each.
Foehn winds - winds that come down from mountains, descend, and warm-up
Santa Ana Winds come from high latitudes east of mountains in California. If winds are strong and there are forest fires, they can make the fires even worse.
Identify the characteristics associated with the Coriolis force.
The earth rotates and creates a force that deflects a moving object on the earth’s surface (to right in northern hemisphere, to left in southern).
Effect increases with distance from equator, and has greatest deflection at poles, none at equator.
Identify the characteristics associated with cyclones and anticyclones in the upper atmosphere, respectively. Focus attention on the type of pressure (high or low), the general speed of the winds (faster or slower), and the direction of Coriolis and pressure gradient forces (inward or outward) for each.
Cyclones - low-pressure center, slower, inspirals (counterclockwise)
Anticyclones - high-pressure center, faster, outspirals (clockwise)
Identify the characteristics associated with winds at the surface. Focus attention on the effects that friction has on winds at the surface.
Friction influences wind direction, working directly against the wind to slow it. A slower wind has a slower Coriolis force. At the surface, three forces combine - pressure gradient force, Coriolis force, and friction.
Identify the characteristics associated with a Hadley cell. Focus attention on the creation of lower pressure belt over the Equator (Intertropical Convergence Zone) and the creation of sub-tropical high pressure belts around 30* N and S latitude.
Rising air at the equator and descending air at 25-30* starts the process of atmospheric circulation, and creates Hadley cell, which is a low-latitude atmospheric circulation cell with rising air over the equatorial trough and sinking air over the subtropical high-pressure belts.
Identify the general characteristics associated with the circulation and movement of air in the mid-latitudes and polar regions. Focus attention on the prevailing winds formed in the mid-latitudes (westerlies), persistent high pressure over the poles creates easterly winds, and where the air from the mid-latitudes meets the air from the poles (in the Northern Hemisphere) forms the polar front.
Hadley Cells create easterly winds along the equator, westerly winds in the mid-latitudes, persistent highs in the sub-tropics and mid-latitudes, and persistent lows in sub-polar areas. Higher pressure at the poles forces air at the surface towards mid-latitudes, creating easterly winds that flow toward persistent sub-polar lows. Where the polar easterlies meet sub-tropic westerlies, the polar front is formed.
