Investigation 8A and 8B 1.) The pressure gradient force directs itself from areas of relatively high pressure to areas of relatively low pressure; the pressure gradient force will be perpendicular to isobars on a surface map. 2.) In the northern hemisphere, the coriolis force is always directed 90 deg. to the right of the observed wind; this results in an air parcel’s apparent tendency to curve toward the right. In the southern hemisphere, the coriolis force is directed 90 deg. to the left of the observed wind; this results in an air parcel’s apparent tendency to curve toward the left. 3.) The frictional force is a force that opposes motion. Therefore, at the surface, the frictional force will direct itself opposite to that of the observed wind. When looking at a station model we can identify the frictional force as being directed towards the tail end of the wind barb. Luckily, for Investigation 8B, you only have to deal with the 500 mb pressure chart. Identifying heights on a 500 mb chart is pretty straightforward: just add a œ0³ to the end of the given 3-digit number. For example, if a station plots a 500 mb height of œ568³, then this would translate to an actual height of 5680 meters. ***Hint*** For number 19 of Investigation 8B., look at Figure 4 and ask yourself, œare the isohypses in the central U.S. generally bulging upward or downward? If you think they are bulging upward, then this would be identified as a œridge; if you think they are bulging downward, then this would be identified as a œtrough. It can be extremely difficult to see the station models on the maps, so remember that you can always open them up here on Blackboard in the œInvestigations Manual Figures folder for a better view.