Handbook for Irrigation of Wine Grapes in South Africa

Chapter 9

can be monitored by means of a handheld anemometer (Fig. 9.5B). Many growers are familiar with the latter instrument, since it is used to measure wind speed for herbicide or pesticide application within the prescribed wind speed thresholds. As an alternative, the Beaufort wind scale may be used to estimate wind speed on land (Table 9.4). This scale is based on the observation of environmental responses in relation to wind speed (Fig. 9.6). Figure 9.4 Figure 9.4 F gure 9.4 Figure 9.4

A

B

FIGURE 9.4. Examples of (A) a relatively inexpensive automatic weather station installed in the proximity of a vineyard and (B) a dry ball-wet ball thermometer (psychrometer) used for determining the dew point temperature.

Figure 9.5

Figure 9.5

A

B

Figure 9.5

Figure 9.5

FIGURE 9.5. Examples of measuring (A) canopy temperature by means of an infrared thermometer and (B) wind speed using a handheld anemometer.

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