How do I determine the changes in pressure with the below diagram? How would I b

Question

How do I determine the changes in pressure with the below diagram? How would I be able to tell the changes in wind direction? Is there any way to tell if there was any precipitation?

Decoding The Meteogram

Now that you have your general bearings, let's move onto decoding the meteogram:

There are three time traces on the upper rectangular graph. The purplish plot represents the variation of surface air temperatures with time. Note, below the first rectangular graph, the series of purplish numbers, which represent the hourly surface air temperatures. I really like this feature and find it quite useful.

The greenish plot shows the time variation of surface dew points. The bluish plot marks the variation of surface relative humidity with time.

Below the hourly temperatures, the green symbols represent precipitation and other restrictions to visibility. These symbols are the same ones that appear on conventional station models. Note the moderate rain observed at the Pittsburgh airport at 15Z on May 20. As an aside, note that the surface relative humidity climbed to nearly 100% once it started to rain at Pittsburgh.

Below weather and restrictions to visibility, the brownish station models allow you to assess cloud cover, surface wind direction and surface wind speed.

When winds are gusty, the maximum wind gust is reported directly above the station model. For example, at 01Z on May 20, the maximum wind gust at Pittsburgh International Airport was 16 knots.

The second rectangular graph includes a plot of horizontal visibility with time (the brown plot). In this case, the visibility at Pittsburgh was 10 miles (read off the scale on the right) from 1951Z on May 19 to 15Z on May 20. Once it started to rain, visibility decreased rapidly, bottoming out at 2 miles between 16 and 17Z on May 20.

The scale on the left represents the heights of cloud bases in feet. At 19Z on May 19, it was overcast over Pittsburgh (note the "O") above 10,000 feet, suggesting an overcast of cirrus (high clouds).

An hour later at 20Z, clouds were "lightly scattered" at 10,000 feet, suggesting some altostratus or altocumulus (middle clouds). "Lightly scattered" may be interpreted similarly to "few". Above 10,000 feet, clouds were broken (probably a broken deck of cirrus).

Okay, look at 13Z on May 20. At this time, clouds were scattered between 3000 and 10000 feet. Clouds were broken at 10,000 feet and overcast above 10,000 feet.

Finally, at 16Z on May 20 (rain had started at Pittsburgh), clouds were lightly scattered between 1000 and 3000 feet (low clouds). Clouds were overcast at 3,000 feet (nimbostratus, for sure).

Below the second rectangular plot at 00Z, 06Z and 12Z, you'll find the highest temperature during the previous six-hour period (in the purplish color). The greenish temperatures at these synoptic times represent the lowest temperature during the previous six-hour period.

The next entry corresponds to the amount of liquid precipitation observed in the six-hour period ending at 00Z, 06Z, 12Z, or 18Z. In this case, 0.21 inches of rain fell at Pittsburgh in the six-hour period ending at 18Z on May 20.

Finally, the third rectangular plot shows the time variation in barometric pressure.

100 TMPF RELH TMPF 90 96 95 84 72 65 59 69 85 9 91 81 72 65 58 69 85 90 89 TXNF 56 93 56 52 VSBC 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 PPO6 T306 CoM 062 0629/12 062918 06 06 063012 0650118 0701/00 070106 0701/12

Explanation / Answer

the pressure may vary from the point ot the point and the location to the location.as we know this that the pressure always increases if we go to depth in case of any fluids and also fpr the case of decreament in the elevation. on the other hand if we are going to the elvated and high altitude then the pressure always decreases. this is happen due to the fact that the as we go up in the atmosphere then the molecules and the density of the air mass also decreases and if we come to the ground level or at the surface of the earth then this air mass density is maximum. due to which the pressure also have it maximum value near the surface.

for the case of the fluids then we can say this that as the depth increases the amount or the volume above the point of observations also increases. due to this the weight also increases per unit area and thus apply the downwards force on this point of observations and thus we can say the pressure is increased there.

pressure also have the great relativity with the precipitations also. as the precipitaion always maximum in the location where the air pressure is low. a low air pressure region will have the low temperature and thus help to condensate and precipitate more easily. the air current or you can say the wind is blowing due to the thermal instablity and differences. as the sun rise, it make some region warm and rest remain in the cold condtions. this make a potential as like electrical potential. this make the air to flow from the high temerature section to the low. in the pressure terminology we can say this as the air flow from the high pressure to the low pressure. the atmosphereic pressure is measured with the help of an instrument which we knwon as barometer.

now here we can see that the meteograph is used to plot the precipiation with the pressure and temperarure relations. in this we have also given the temperatures and the dew point along with the elevations of the thermal potentials.

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