Climate and microclimate (7m 28s)
Okay, this is the climate and microclimate video. Here we’ll talk a little about climate and microclimates and then ill offer a few design strategies for different types of climates.
Climate is weather conditions in a general area over a long period of time. These conditions are based on conditions in the earth’s atmosphere, the earth’s rotation around the sun and the tilt of her axis, among other things.
The moon creates ocean currents and tides. On earth – Volcanoes, oceans, wind, water bodies, forest/trees, building and people. And everything sort of plays into this aggregate… climate. Elevation plays a role. For every 200 meters gain there is a 1º temperature drop.
And of course humans, humans burn fossil fuels, we increase the expansion of the greenhouse effect and thus trapping more heat in the atmosphere
There’s this great youtube video where this guy takes this big blue flexi material and puts it around in a circle and he puts marbles into the material. These marbles end up mimicking the direction of orbit of planets.
“When you study the solar system, all the planets are going around the sun in the same way, why is that? Why is everything going in the same direction? Well, the answer is it wasn’t. Different directions. But there was a preferred direction. And if one had a slight preference going one way versus another then things going the opposite way got eliminated and when it’s all said and done, everything’s going the same way… that usually works 90% of the time [in reference to the marbles].”
So that’s the macro scale. Now let’s look at microclimates. Microclimates are changes in moisture level or climate on a smaller scale within a site.
Worms wriggling through the soil creates microclimate. Behind the worm they leave a gap of air and this air aerates the soil and it improves the soil. Ponds create microclimates. Ponds absorb heat, they retain heat from the day and it changes the temperature around that pond. A garden has to provide microclimates or else nothing would grow. That’s what mulch is, it’s shade that creates microclimates to enable the growth of plants.
There’s a good activity that we do during design courses where we all stand in a line and hold hands and then you have somebody up front who guides the whole class through this site, whatever permaculture site we’re at. So everybody closes their eyes and walks silently throughout the whole site. Even in this short time, you start to become aware of all the other sounds and textures under your feet and the smells and all the other things happening beyond the visual sense. Doing this activity reall brings awareness of the microclimates. When you walk from the forest onto a path, or vice versa you can notice on other levels how the microclimate changes, soft, changes in the wind, the wind direction or the sounds or… microclimates are all the subtleties that are happening in a space.
Climatic zones and design strategies
There are three major zones. We have tropical, subtropical. Then we’ll talk about temperate or high elevation climates and we have arid climates. There are only slight variations between each. Tropical environments, usually they have 3-4 growing seasons. It’s hot warm, rainy season, constant temperature. In tropical regions, there are no months under 18ºC. In subtropical regions, it will frost maybe only in the coldest months. There’s a lot of rainfall, up to 400cm per year. This is where condensation exceeds evaporation. There’s more [moisture] coming in than is leaving. The soil is thin because it breaks down very fast and it’s fungi based as opposed to bacteria based soil in temperate climates. As far as a contrast for the amount of potential growth in a tropical versus a temperate forest. In areas which can support 180 species in a tropical forest, can support about 10 species in a temperate forest. I’ve heard this statistic from a few people… this says there is 18 times as much life in a tropical forest than a temperate forest.
A few design strategies for tropical areas. You’re mainly looking to design against flood prevention and water retention. So to do this you’ll want to make a good earthworks design which we’ll talk about next chapter. To catch rainwater and try to trap it in the soil. You also want to focus on building soil by planting perennials or legumes or other pioneer species.
In temperate or high elevation climates, there is usually 1-2 growing seasons. There’s a short summer growing season and a long winter with freezing temperatures. In temperate climates you have thicker topsoil because it doesn’t break down as fast. And the soil is bacteria based.
For design strategies on temperate climates, it’s mainly building with insulation. Which we’ll talk about more in the natural building videos. And then in desert or arid climates, there is usually 0 or maybe 1 growing season, high temperature flocculation, long hot summer and a short cool winter.
Usually the rainfall in desert areas is less than 25 centimeters per year. In these conditions, evaporation exceeds precipitation. There may be little to no topsoil. So the whole strategy for desert or arid environments is water retention. And also protecting from fire but mainly water retention. So you want to install narrow, deep ponds instead of shallower or wide ponds. YOU want to create shade, plant windbreaks, lay thick mulch at least 30cm. Grow groundcovers, grow aquatic plants in water bodies, dig swales, vines on a trellis or a polytunnel to create shade. To protect yourself from fire and wind, plant windbreaks, like shrubs or hedges or build round structures to protect from high winds.
Although most of my experience has been from cold or hot climates, I’m not sure there’s that much difference between cold and hot climates. Sure, soil type is different, types of plants will be different definitely, in cold climates you want to insulate a bit more, in the tropics, the soil is going to chew itself about 10 times as fast, but these are minor things. No matter the climate, you still need to build soil, you still need a toilet, you still want to plant trees, and so on. The principles remain the same.
So that is my understanding of the climate and microclimate chapter. A lot of it is just observation and being aware of how we can change the climate and change the climate within our own site. And also a few strategies on general design.
This concludes the climate and microclimate video, thank you for your time.