Quiz #2 Study Guide
Air pressure can simply be measured with a barometer by measuring how the level of a liquid An Ideal Gas behaves in such a way that the relationship between pressure (P), Since pressure changes from place to place, owing to weather. 6) The Coriolis force is strongest when the wind speed is ______ and the latitude is 8) What is the driving force of weather on earth? wind sun air pressure rain. net force on air "parcels" due to pressure differences between one side of them use weather maps to visualize relations between pressure and wind patterns?.
How should we interpret isobars on a contour map of pressure map?
How can we interpret the pressure-gradient force on a pressure map? Winds and Pressure Patterns: Over land, winds do generally blow faster where the PGF is stronger isobars are closer together Over oceans, winds do generally blow faster where the PGF is stronger isobars are closer together Winds over oceans are generally faster than winds over land for the same PGF can explain this by noting that friction is greater over land than oceans because land is rougher--it has vegetation, hills and mountains, buildings, etc.
The Weather Quiz
Near the earth's surface in the Northern Hemisphere, maps showing winds and pressure patterns isobars show that winds don't typically blow perpendicular to isobars toward their lower pressure side, but instead blow at an angle skewed somewhat to the right clockwise relative what we'd expect. In the Northern Hemisphere aloft the discrepancy is even greater: Coriolis effect We observe moving things for example, air parcels and lots of other things from the perspective of the earth, which is rotating while we make our observations.
Hence we, the observers, are following a gradually curving path through space while we watch things move relative to us.
Even if no net force acts on a moving object, so that its motion doesn't change according to the Principle of Conservation of Momentumwe observe it to follow what appears to be a curved deflected path the object is following a curved path--instead, we are, but we just don't perceive it!
Illustrations of the Coriolis effect YouTube Movie: Some guys play catch on a rotating merry-go-round According to the Principle of Conservation of Momentum, any object that follows a curving path is changing its motion and therefore must have a net force pushing on it. To account for the apparent deflection of moving objects, we invent a fake force, the Coriolis force: Aloft, the winds blow so that the Coriolis "force" pushing on moving air to its right appears approximately to balance the PGF pushing on it toward lower pressure animation of combined effects of PGF and Coriolis force without friction the resulting wind is called the geostrophic wind examples at mb level there is a relatively narrow zone of large PGF aloft at midlatitudes, where the geostrophic winds are correspondingly faster and blow eastward on the average the jet stream At the surface, the winds blow so that the Coriolis "force" pushing on moving air to its rightthe PGF pushing on air toward lower pressureand friction pushing against the direction of the wind, trying to slow it downproduces distinctive wind patterns Lab Exploration 6: Pressure at any level in the atmosphere must approximately support the weight of air above that level that is, approximately balance the force of gravity pulling down on the air above that level.
Since the total weight of air above you decreases as you go higher in the atmosphere, it follows that the pressure must decrease as you go higher, too. Of course, this is what we observe. When air in the lower troposphere warms, it expands and lifts air sitting on top of it upward. At any particular level above the warmed air below, some air that started below that level will be lifted up past that level.
This increases the amount of air above that level, and hence the weight of air above that level.
What is the relationship between temperature, air pressure, wind and moisture?
This requires that the pressure at that level, pushing upward, must increase to support the increased weight of air above that level. When air in the lower troposphere cools, it contracts and air sitting on top of it drops lower At any particular level above the cooled air below, some air that started above that level will drop below that level.
This decreases the amount of air above that level, and hence the weight of air above that level. This requires that the pressure at that level, pushing upward, needed to support the decreased weight of air above that level, must decrease. Consequently, there must be a relationship between the temperature of air in the lower troposphere relative to surrounding areas and the pressure aloft relative to surrounding areas at the same level aloft.
Where the lower troposphere is relatively warm compared to surrounding areasthe pressure aloft, above the relatively warm air, must be relatively high compared to surrounding areas at the same level aloft Where the lower troposphere is relatively cool compared to surrounding areasthe pressure aloft, above the relatively cool air, must be relatively low compared to surrounding areas at the same level aloft As observational evidence that this is true, note how similar the patterns shown on these two maps are: Can't add air through the top of a column it has no true top Can't add air through the bottom up through the ocean or land surface Can add air through the sides of the column wind!
Quiz #1 Study Guide
However, wind by itself isn't enough, because air can be entering and leaving different parts of the column at the same rate, producing no net change in the amount of air in the column Must have air entering the column faster than it is leaving convergence of winds or leaving faster than it is entering divergence of winds.
Winds converging in an areas adds air to a column, increasing its weight and increasing the surface pressure. Relatively high surface pressures develop where winds aloft converge Relatively low surface pressures develop where winds aloft diverge.
Isobars and isotherms one of each is shown in the figure below. Small horizontal differences in pressure cause the wind to blow. Air motions around high and low pressure centers northern hemisphere.
- Air & Wind Quiz
Would you expect the air at Pt. A to be warmer or colder than at Pt. Rising air motions, what can cause air to rise and why rising air is important. Strong and weak pressure gradients and their effects. Cross-sectional structure of cold and warm fronts such as shown below. You will not have to locate a front on a surface map like was done in class, though I might draw a front and ask you what type it is.
Upper level charts pts. What is an upper level chart, how do they differ from surface maps?
What instrument is used to measure air pressure? About when was it invented? What relationship is there between the rate of pressure decrease and air density i. Layers of the atmosphere 15 pts. Approximate altitudes of these layers.
Ideal Gas Law 10 pts. This is a microscopic-scale explanation of air pressure. R and k are both constants you can pretty much ignore them. You should be able to determine what will happen to the pressure in a rigid container or something flexible like a balloon if you change the variables in the equation above.