One evening this summer while enjoying a glass of wine on the terrace of a trattoria in the Piemonte region of Italy the quiet tranquillity of the evening was interrupted by a loud bang. It sounded like a gunshot coming from across the rolling hills of vineyards. 10 minutes or so later another loud bang followed and so on until our curiosity could be supressed no longer and we asked the trattoria owner if they knew the source of the bangs. She told us with enthusiasm that a thunder storm was coming and pointed out across the hills.
Sure enough we could see black clouds hugging the curved horizon. She went on to explain that a group of local vineyard owners had clubbed together and invested in some ‘hail cannons’ (google it) to protect their precious delicate grape harvests from the elements. The theory is the cannons blast shockwaves into the clouds of an approaching storm which breaks up the hail stones before they fall from the sky. Apparently these ‘hail cannons’ have been used since the 19th century. So these vineyard owners were directly influencing and creating their own microclimate.
This episode got me thinking about how we as landscape architects work with, influence and yes I suppose battle with microclimates on a day to day basis, although we perhaps don’t take arms against the elements in quite such a literal fashion as these Italian winemakers.
In our analysis of a site we consider aspect, topography, exposure, sun, shade, rainfall, wind direction, drainage and how all these elements combine to produce a microclimate which we need to understand so we can design accordingly for the desire outcome. It could be choosing the right plant species for a shady dry site or identifying a sunny seating area. Or it could be perhaps finding opportunities to create or influence microclimates to make them more hospitable by planting trees for shade, incorporating a wind shelter in a windy street, providing a water feature for hot city dwellers to cool off in or create a sunny sheltered walled garden to grow fruit or tender plants.
Proof of man influencing microclimates is evident in our landscapes, towns and gardens and has been for centuries. The flat south coast plain where I live is criss-crossed with straight regimented lines of Poplar tree belts where farmers have been attempting to abate the fierce off shore winds that whip across the flat land.
A newly renovated pub near me swiftly learnt this lesson too when they found no one could sit in their new lovely south east facing pub garden that fronted flat open fields and promptly installed wind barriers.
Last week my work was influenced in quite a different way by microclimate. Out undertaking fieldwork to identify views to a valley bottom village in the South Downs National Park the weather changed suddenly.
Clouds spilled over the rolling hills of the South Downs, sinking and settling into the bottom of the Arun valley. Valley fog forming in low points like this is the result of a temperature inversion caused by heavier cold air settling into the valley, with warmer air passing over the hills above. The fog is confined by the local topography and can last for days. Well that was the end of my fieldwork for the day – unfortunately I forgot to pack my fog cannon!