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Geography Question

In relation to a woodland micrclimate:

1) What is the transmission coefficient?

2) How is this calculated?

3) Any other information?

I'm baffled and can't find any information anywhere. :frown:
Reply 1
Avatar for tom c
tom c
I think that the transmision co-efficiant is something related to the albedo(reflectifness) of the woodlands. Infra red readiation from the sun will be blocked to a certain extent by the foliage of a woodland meaning that in summer the woodland is often cooler than the open ground. The transmission coefficiant is something like the percentage of light absorbed and there is a formula I have seen before. This may be wrong though as it is a vauge memory.

hope this helps
Yes kind of, any idea on the formula??
Reply 3
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tom c
I will try and get the formula for you at school tomorrow as a print out and i will put some info on this thread including the calculations. We have a database with quite a bit on microclimates.
tom c
I will try and get the formula for you at school tomorrow as a print out and i will put some info on this thread including the calculations. We have a database with quite a bit on microclimates.


Yeah that would excellent, look forward to it :smile:
Reply 5
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tom c
Here is some general info:

solar radiation on average trees reflect around 30% of solar radiation falling on them but sunflecking takes place where there are gaps in the canopy and patches of sunlight reach the floor, for example in a beech or oak woodland. the transsmission of light is highly dependant on the type of tree (eg 50% oak in winter and 20-30% in summer where leaves block). For a spruce forest it can be as little as 5% all year round. Clearly this has an impact on the temperatures and ground , herb and shrub layers (serveys of species % and diversity possible). The light meter results are best converted into a transmission coefficiant, i.e. the ratio between the light level at a sample point inside the woodland (L1) and then recording outside in the control (L2), therefore TC= L1/L2. Then isopleth maps can be constructed and analysed to show variation. these results can be related to photographs taken vertically upwards and gridded to determine the relative proportion of dark (i.e. canopy) and light areas. Correlations using rs between TC and % canopy can be made for the sample points in each quadrat.

hope this helps. :eek:
Thats just what i wanted, thanks very much, really appreciated! :biggrin: :smile: :cool: :tongue:

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