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Weather Station
(Monitoring conditions in the laboratory)

Work task and measurement procedure

Work task:

  1. Determine at a given time the values of temperature, absolute air pressure, air pressure converted to sea level and humidity in the laboratory. Make a note of them, including the current measurement time.

  2. Compare the obtained pressure value converted to sea level with the official current value of a professional local meteorological station (Klatovy, Czech Republic). Compare the twenty-four-hour trend of this pressure.

  3. From the measured values of atmospheric pressures (absolute pressure and pressure switch to the main sea) and possibly also temperatures, estimate the altitude of our meteorological station using available formulas (see Theory). Consider the result from relation (1) as the most accurate value, discuss the accuracy of other results against this value.

  4. Use internet maps to determine the altitude of the entrance to the J. Vrchlický Grammar School in Klatovy. From the knowledge of the altitude of our meteorological station (see point (3)), determine the floor in which the remote GENIE experiment is located.

  5. Determine the absolute humidity in the laboratory from the value of relative humidity, the current temperature and the table of absolute humidity of saturated steam (see below)

  6. According to relation (4), determine the current dew point of the air in the laboratory. Compare this value and discuss it with the value from a simpler (but less accurate) formula (again, see Theory).

Table of absolute humidity of saturated steam with a given temperature
 t / °C   Φm / g·m–3   t / °C   Φm / g·m–3   t / °C   Φm / g·m–3 
–10 2,15 8 8,28 26 24,37
–9 2,33 9 8,83 27 25,76
–8 2,53 10 9,40 28 27,23
–7 2,75 11 10,01 29 28,75
–6 2,99 12 10,66 30 30,35
–5 3,25 13 11,35 31 32,07
–4 3,53 14 12,06 32 33,85
–3 3,83 15 12,82 33 35,71
–2 4,14 16 13,63 34 37,67
–1 4,49 17 14,48 35 39,71
0 4,85 18 15,36 36 41,84
1 5,20 19 16,29 37 44,08
2 5,57 20 17,29 38 46,42
3 5,95 21 18,32 39 48,86
4 6,37 22 19,41 40 51,41
5 6,80 23 20,57 41 54,07
6 7,27 24 21,78 42 56,84
7 7,79 25 23,04 43 59,73

Measurement procedure

  1. We'll run a remote GENIE experiment.

  2. We record the current values of the measured quantities as well as the current time data.

  3. We will search the Internet for one of the official meteorological stations that are as close as possible to the building of the J. Vrchlického Grammar School in Klatovy (GPS: N 49°23.501', E 13°17.938') and find current data for comparison.

  4. We compare the data with each other. If we also obtain data on the development of the atmospheric pressure trend, we will also compare these data.

  5. We express the expression for obtaining the altitude from formula (1) and substitute valid values of absolute pressure and pressure converted to sea level. Similarly, we can obtain values of altitudes from both remaining formulas – a simplified expression without the current temperature and the formula according to J. Babinet

  6. Determine the percentage deviations of the 'less accurate values' of altitude from the 'exact value' obtained by formula (1). We determine whether it is possible (under the given conditions) to use one of the simpler terms for common use.

  7. We will look for the altitude around the building of the J. Vrchlický Grammar School in Klatovy (GPS: N 49°23.501', E 13°17.938'). in open sources (eg internet maps).

  8. We estimate the floor in which the remote GENIE experiment is located, from the difference between the altitude determined by the calculation and the altitude of the terrain around the school.

  9. Find the value corresponding to the maximum possible absolute humidity Φm at a given temperature according to the current value of the laboratory temperature in the table of absolute humidity of saturated steam (see above).

  10. We substitute the value of the maximum absolute humidity Φm together with the value of the current relative humidity φ in the laboratory into the formula (3) – thus we obtain the value of the absolute humidity in the laboratory.

  11. We calculate the dew point value tRB by substituting the current temperature and relative humidity into formula (4). Similarly, we can obtain a guide value from a simplified formula. We compare this value with the value from formula (4) – we decide whether it is possible to use a simpler expression for common purposes under the given conditions.

  12. We check whether the dew point temperature and the absolute humidity in the laboratory correspond to each other in the table of absolute humidity of saturated steam.