Frequently Asked Questions

If you have a question that isn't answered here please contact us so we can help you and improve this page for others.

How is the work you do on my property outside the frost season going to assist me during a frost event?

We are studying relative patterns of temperature distribution at night across your property. During strong radiative cooling situations (typical of radiative frost events) the same relative patterns will develop irrespective of time of the year. The coolest areas of your property during a clear still night in February will be the same as the coolest in October. The other parameters of wind drift direction and inversion strength are governed largely by topography and so given similar weather conditions the directions and strengths of these are consistent.

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What effect do shelter belts have?

Shelter belts have variable effects, sometimes positive, sometimes negative, but their effects are usually not as great as people think. When shelter belts are particularly thick or dense they can dam and locally redirect cold air. Their effects are site specific and need to be addressed in this manner.

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How many temperature loggers and masts do you put up?

This varies depending on the size of the property. A higher density of equipment will be deployed where topography on or surrounding the property is complex. On smaller blocks one instrument tower is usually sufficient in combination with 20 - 25 temperature data loggers. On larger blocks (100ha) up to four instrument towers and 75 - 90 temperature data loggers are usually required.

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How high are the masts you deploy on site to monitor inversion strengths and wind speeds?

Our masts are 15.0m high. Temperature is recorded at 15.0m and 1.0m (vine height) but is varied for orchard situations where fruiting heights are higher. Wind speed and direction are recorded at 8.0m, high enough to ivercome friction from vegetation and minor topographic irregularities.

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Some wind machines have shown to be effective in pulling down air from as high as 20m or greater so how representative are results from a 15m mast?

Much of the warming associated within an inversion occurs within the first 10.0m above ground. Temperatures may increase further at greater heights but the rate of increase usually becomes incrementally less. If we don't find a significant warming profile within the first 15.0m above ground then it is unlikely to be of significant value to frost mitigation if it is higher up.

Furthermore by the time warm air is pulled down from greater heights it is of limited benefit to frost fighting closer to the ground. It becomes increasingly difficult to mechanically bring down warmer air and mix it with cooler surface air when the inversion is higher above the ground.

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I thought inversion strengths varied from one frost night to the next?

They do, and they also vary in strength constantly through any given night. But when measured continuously we are able to discern a mean strength and this varies from site to site. The presence of cloud, water vapor and especially speed of wind drift greatly affect inversion strength. This is why we must ensure that data is representative of your property and of events that take place under strong radiative conditions, as this is when you are most likely to get a frost.

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If I have a neighbour who is interested in having a property surveyed can we have them both done and share the costs?

Yes! A significant saving can be made in this way. Please contact us to arrange a quote.