NATS 101 Quiz 1 Study Guide

Approximately 60% of the questions on Quiz #1 come from topics on this study guide, the remaining 40% will come from material on the Practice Quiz Study Guide .

*** Chap. 1 (pps 8-13), Chap. 6 (pps 143-148) ***
Mass, weight, density, and pressure. Mass is the amount of a particular substance. On the earth gravity pulls downward on a mass producing weight. Pressure at any level in the atmosphere is a measure of the weight of the air above (this is one way of thinking about and understanding pressure). Pressure is defined as force divided by area and acts like a force (a force that pushes upward, downward, and sideways). Common pressure units and typical sea level pressure values. What instrument is used to measure air pressure? About when was it invented? Pressure and air density (density = mass divided by volume) both decrease with increasing altitude (you should be able to explain why). What relationship is there between the rate of pressure decrease and air density (i.e. does pressure decrease most rapidly in high or low density air)?

Sample questions
Practice Quiz: 15, EC2, EC3          Quiz #1: 3, 17          Final Exam: 6, 11,

Ideal Gas Law. This is a microscopic scale way of thinking about what causes air pressure. Two equations P = N k T / V and P = (rho) R T.  N is the number of air molecules in a volume V. T is temperature and  rho is density.  R and k are both constants.  What will happen to the pressure in a balloon if you change the variables in the equation above? What variables could you change together in such a way that the pressure would stay constant?

Ideal gas law applications.  If you heat or cool a parcel of air in the atmosphere, Charles' law says the density (volume) will change in such a way that the air pressure inside the parcel remains constant (remains the same as the pressure of the air surrounding the parcel).

Upward and downward forces act on air parcels (the strength of one of the forces depends on the air inside the parcel, the other on the air outside the parcel). These two forces are usually in balance. What happens to the balance when you warm or cool a parcel of air?  Basically you should be able to explain why a balloon of hot low density air rises and a balloon of cold high density air sinks.

Sample questions
Quiz #1: 13, 14, 16            Final Exam: 22, 41

*** Chap. 1 (pps 13-18), Chap. 6 (pps 141-149), Appendix C (pps 431-432) ***
Station model notation. Cloud cover, temperature, dew point temperature (typical values for Tucson), wind direction and speed, common weather symbols (rain, snow, fog, rain shower, thunderstorm, tropical storm and hurricane), pressure. Units. After pressure is measured, what important adjustment is made before the pressure is plotted on the surface map? Why is that necessary? Average value and typical range of sea-level pressures.

Surface weather maps. Surface observations are made and a new map is prepared hourly. What time zone or time reference is used? 24-hour clock (what time is it when it is 17:30 in Tucson). Isobars and isotherms. Small horizontal differences in pressure cause the wind to blow. Air motions around high and low pressure centers (northern hemisphere). Strong and weak pressure gradients. Convergence and divergence. Rising and sinking air motions. How do wind motions around highs and low affect the temperature pattern? Cold fronts and warm fronts.

There won't be any questions on Quiz #1 from the following section:
Upper level charts
Ridges (warm air below) and troughs (cold air below). Winds blow parallel to contour lines and from west to east. Would upper-level convergence cause surface pressure to increase or decrease?

Sample questions
Practice Quiz: 2, 10, 11, 14, 19            Quiz #1: 6, 7, 8, 9, 10, 11             Final Exam: 3, 7, 10, 17, 26?, 34, 52

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ILC 141
Harvill 318
Harvill 302