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kb:lad [2012/08/15 22:27] – enviadminkb:lad [2017/11/10 09:25] (current) – external edit 127.0.0.1
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 ====== Obtaining Leaf Area Density Data ====== ====== Obtaining Leaf Area Density Data ======
-{{:kb:leafs_at_treee.jpg?300 |Leafs on a tree}}+{{:kb:leafs_at_treee.jpg?350 |Leafs on a tree}}
 The **Leaf Area Density (LAD)** is the portion of leaf surface ($m^2$) within a volume of air ($m^3$). The formal unit is  The **Leaf Area Density (LAD)** is the portion of leaf surface ($m^2$) within a volume of air ($m^3$). The formal unit is 
 $$ \frac{ \text{Leaf surface } (m^2)}{ \text {Reference volume } (m^3)} $$ $$ \frac{ \text{Leaf surface } (m^2)}{ \text {Reference volume } (m^3)} $$
  
-In ENVI-met, like in most other models, the LAD is counted **one-sided** which means that only one side of the leaf is counted as active surface area. This accounts to the fact, that most plants only have stomata on one side of the leaf, typically on the back (but there are others as well). So for the exchange of latent heat ($LE$) it makes sense to count only one side of the leaf as active surface. Also, for the exchange of sensible heat ($H$), normally only one side is exposed to the wind while the other is in the lee of the leaf so that its exchange coeficient approaches zero. This is - of course- a simplicifcation which can be discussed.    +In ENVI-met, like in most other models, the LAD is counted **one-sided** which means that only one side of the leaf is counted as active surface area. This accounts to the fact, that most plants only have [[wp>Stoma|stoma]] on one side of the leaf, typically on the back (but there are others as well). So for the exchange of latent heat ($LE$) it makes sense to count only one side of the leaf as active surface. Also, for the exchange of sensible heat ($H$), normally only one side is exposed to the wind while the other is in the lee of the leaf so that its exchange coeficient approaches zero. This is - of course- a simplicifcation which can be discussed.    
  
 ===== Objective ===== ===== Objective =====
  
-One of the most frequently asked questions is "How do I get an LAD profile for my plant?"+One of the most frequently asked questions is "//How do I get an LAD profile for my plant?//"
  
 First, I have to admit that the original LAD profiles provided by ENVI-met are rather hand made and based on only a few reference profiles. \\ First, I have to admit that the original LAD profiles provided by ENVI-met are rather hand made and based on only a few reference profiles. \\