Fig. 6-CO, p.140 Note both: straight line curved motion of winds (acceleration, therefore force(s) acting) Four Forces: Pressure gradient force (PGF) Frictional force (FF) Centripetal force (CP) Coriolis force/effect (CF)

Fig. 6-9, p.150 Pressure force = (say) a few inches of water Acting over a distance of (say) a few feet Pressure gradient force = Pressure force/distance

Fig. 6-10, p.151 Pressure force = 1020 mb – 1016 mb = 4 mb Acting over a distance of 100 km Pressure gradient force = Pressure force/distance = 4 mb/100km Lines joining points of equal (iso) barometric pressure (bar)

Fig. 6-11, p.151 Point 1 Point 2 On a larger scale WX map we see that the “straight” isobars of the previous slide are actually part of a larger curved isobar High Pressure system

Fig. 6-13, p.152

Fig. 6-14, p.153 NN Stationary earthRotating earth Imagine missile being fired from N. pole in your direction.

Fig. 6-15, p.154 Now consider 2 forces acting on upper level winds: 1.PGF makes the air start moving from high to low pressure. 2.Once it starts to move the CF kicks in and makes it veer to the right (in the NH). It keeps on veering to right until it is exactly balanced by PGF. 3.The net result of these 2 forces (Newton’s first law) is that the air moves parallel to the contours, not from H to L, as we might have expected. 4.Upper level flow parallel to straight contours like this is called geostrophic. 5.Look at any upper level chart and you’ll see that the air moves parallel to the contours.

Fig. 6-17, p.155 Now consider 3 forces acting on upper level winds moving around a circle (PGF, CF and centripetal force): 1.PGF makes the air start moving from high to low pressure. 2.Once it starts to move the CF kicks in and makes it veer to the right (in the NH). 3.Because it is constantly changing direction to circle the Low (for example) the air must be subject to a force pushing it towards the center: the centripetal force (see small black arrow label Net”). 4.The net result of these 3 forces (PGF + centripetal = CF; Newton’s first law) is that the air moves in a circular pattern parallel to the contours, not from H to L. 5.Upper level flow around H or L, parallel to curved contours is called gradient wind. 6.Look at any upper level chart and you’ll see that the air moves around a Low (counterclockwise) and around High (clockwise), both in the NH. Gradient wind (curved flow around L and H)

Fig. 6-16, p The closer the contours, the stronger the gradient and therefore the higher the wind speed. 2.The faster the air, the stronger the CF, which must be true if it is to balance the higher PGF (Newton’s first law).

p.157

Fig. 6-18, p.156 Contours lines in meters Often isotherms, in degrees C, also plotted on upper level charts Roughly meridional flow directionRoughly zonal flow direction

p.149 Arizona Montana

Fig. 6-8, p.148

Fig. 6-19, p.159

Fig. 6-12, p.152 Station model: see

Fig. 6-21, p.160

Fig. 6-3, p.145 Decode pressure in station model: 1.Add decimal point – Now add leading 9 or 10 – mb or mb 3.Decide which is realistic based on typical observations – only mb makes any sense

Fig. 6-7, p.147 Add 10 mb per 100m of elevation to correct observed station pressure to adjusted sea level pressure (ASLP)

Fig. 6-4, p.146 You could replace toxic mercury with nontoxic water but then the column would be about 32 ft tall and you’d need to read it from the 3 rd floor window. 32 ft of water

Fig. 6-5, p.146

Fig. 6-23, p.161 Or zero degrees

Fig. 6-25, p.162 A wind rose Note alignment of runways at both TIA and Davis Monthan along the most prevalent wind direction

Fig. 6-26, p.162

Fig. 6-27, p.162