1 Measuring Climate Main Components: Radiation Temperature Humidity(Wind)

2 Macro- or localclimateGlobal climate Macro- or localclimate Microclimate Microclimate is the complex of environmental variables to which plants are exposed like temperature, radiation, humidity and wind Microclimate is important and strongly influences the presence of vegetation

3 Radiation: Star PyranometerThe source of energy for photosynthesis and bioproductivity is solar energy Star Pyranometer The glass dome admits electromagnetic radiation between 0.3 and 3 µm, where the proportion of PAR (400 to 700 nm) is about 50 %

4 Albedo: Albedo is the fraction of incident radiation reflected by a surface, it can is calculated by the formula: Albedo = reflected radiation /global radiation An albedometer is essentially a combination of two star pyranometers, one facing upward and one facing downward.

5 Temperature: Resistive temperature detectors (RTD)Liquid (mercury) in glass thermometers are common instruments in meteorological stations but their dissadvantage in our case is the the lack of a facility for recording Most temperature sensors depend on the fact that changing temperature alter the electrical properties of a certain material Resistive temperature detectors (RTD) Platinum resistance thermometers (PRTs)

6 PT1000 sensors have a resistance 1000 ohms at 0 °CPT100 have a resistance of 100 ohms at 0 °C and 138,4 ohms at 100°C (0,384 ohms =1 °C) PT1000 sensors have a resistance 1000 ohms at 0 °C Sources of errror in measuring temperature: Incoming radiation Thermal mass of sensor

7 Humidity: Absolute humidity: Relative humidity (RH %):(gram of water vapor per cubic metervolume of air) Relative humidity (RH %): Amount of water vapor that air is holding compared to the amount it can hold at a specific temperature expressed in percent Mechanical Hygrometers Utilise change in dimensions of materials (hair) Electrical Hygrometers Measure changes in electrical capacitance or resistance of hygroscopic material, as the material will absorb or desorb water depending on the vapor pressure in the atmosphere thus changing ist electrical properties

8 Psychrometer (Wet- and Dry-Bulb Hygrometer)Dew-Point Sensors Optical sensors cool a surface (mirror) until condensation starts to form, thus indicating the dew-point. From this dew-point temperature and the temperature of the air RH can be calculated. Psychrometer (Wet- and Dry-Bulb Hygrometer) A pair temperatur sensors placed in an air stream, one (the wet bulb) is covered with a wet wick; evaporation causes a lower temperature at this „wet“ thermometer than at the other “dry“ thermometer. The difference in these temperatures can be used to calculate the relative humidity of air RH = 100*VP/SVP(TT) RH = relative humidity (Relative Luftfeuchtigkeit) in %; VP = actual vapourpressure (aktueller Dampfdruck) in mbar SVP = vapourpresssure at saturation over water (Sätigungsdampfdruck) über Wasser in mbar

9 Calculation of relative humidity (RH%) from dry an wet bulb temperature: (Principle according to Assmann): RH = 100*VP/SVP(TT) (F7) RH = relative humidity (Relative Luftfeuchtigkeit) in %; VP = actual vapourpressure (aktueller Dampfdruck) in mbar SVP = vapourpresssure at saturation over water (Sätigungsdampfdruck) über Wasser in mbar VP = SVP(HT) – C * SP * (TT – HT) (F3) TT = Airtemperature of dry bulb (Lufttemperatur des trockenen Thermometers (Pt 100)) Basics 2017: TT= channel 11 (Kanal 11) HT = Temperature of wet bulb (Temperatur des feuchten Thermometers (Pt 100)) Basics 2017: HT= channel 12 (Kanal 12) SVP(HT) = C1 * EXP(C2 * HT/(C3 + HT)) (F4) SVP(TT) = C1 * EXP(C2 * TT/(C3 + TT)) (F1) C1 = 6,10780 C2 = 17,08085 C3 = 234,175 RH % =100 * (C1*EXP(C2*HT/(C3+HT)) - (C) * (SP*(TT-HT)))) / (C1*EXP((C2)*TT/(C3+TT))) C = 0, * (1 + 0,00115*HT) Psychrometerkoeffizient in °C-1 SP = 1013,246 mbar RH % =100*(6,1078*EXP(17,08085*HT/(234,175+HT))-(0,00066*(1+0,00115*HT)*(1013,246*(TT-HT))))/(6,1078*EXP((17,08085)*TT/(234,175+TT))) Literatur: Deutscher Wetterdienst (Hrsg.) 1979: Aspirations-Psychrometer-Tafeln. Herausgegeben vom Deutschen Wetterdienst, 6., durchgesehene und erweiterte Auflage, Friedr. Vieweg & Sohn Braunschweig/Wiesbaden. 253 Seiten

10 LOGGER: Programm Schanze 11Basic Methods in Plant Physiology, Anatomy and Ecology SS 2017 Site: Greenhouse II (Rollhaus) LOGGER: Programm Schanze 11 Channel: (K) Type of measurement and position of sensor: Method: Channel: Label: Dimension: K 11 K 12 RH (after Assman) at upper surface of canopy (1,1m) Pt 100 (Temp. of dry bulb) Pt 100 (Temp. of wet bulb) CH 11 CH 12 p50 p50_k °C K 17 Temp. (air) at 1,1m same level as RH Pt 100 CH 17 P20_k K 21 Temp. in pot Cl. min. 2 tr/hell (pot diam. 27cm) CH 21 bt0 K 22 Temp. in pot Cl. ros. 2 tr/hell (pot diam. 27cm) CH 22 bt5 K 26 Temp. in pot Cl. mex. 2 tr/hell (pot diam. 22cm) CH 26 bt10 K 27 Temp. in pot Cl. min.1 tr/hell (pot diam. 27cm) CH 27 bt20 K 31 „global“ radiation + additional light at 1,1m (upper surface of canopy) Dualpyranometer CH 31 A5080_o W/dm2 K 32 Albedo at 1,1m CH 32 A5080_u K 39 Radiation at 0,3m (base of canopy) Starpyranometer CH 39 G8240

11 Basic Methods in Plant Physiology, Anatomy and Ecology SS 2017Site: SCHATTENHALLE LOGGER: Programm oeko2014 Kanal: Type of measurement and position of sensor Method: Channel: Label: Dimension: K 2 Temp. in pot Cl. ros. 2 feucht/dunkel (pot diam. 22cm) Pt 100 CH 2 Bt10st1 °C K6 Temp. in pot Cl. min. 2 feucht/dunkel (pot diam. 22cm) CH6 bt30st1 K 7 Temp. in pot Cl. mex. 2 feucht/dunkel (pot diam. 22cm) CH 7 bt0st2 K 35 Radiation at 1,5m Starpyranometer CH 35 G2231st1 W/dm2 K 36 Radiation at 0,9 m CH 36 G3651st2 K 51 Temp. (air) at 1,4 m CH 51 LTEMPst1 K 56 Relative humidity (RH) % at 1,7m Capacitance hygrometer CH 56 Feucht1 % RH