Added some documentation

src/main/java/no/nibio/vips/model/naerstadmodel/NaerstadModelBackgroundDataMatrix.java

@@ -25,24 +25,24 @@ package no.nibio.vips.model.naerstadmodel;
  */
 public class NaerstadModelBackgroundDataMatrix extends no.nibio.vips.util.DateMap{
 
-    public final static String TSHH = "TSHH";
-    public final static String SPH = "SPH";
-    public final static String VAS = "VAS";
-    public final static String WVD = "WVD";
-    public final static String VRS = "VRS";
-    public final static String TSWH = "TSWH";
-    public final static String WD = "WD";
-    public final static String WHS = "WHS";
-    public final static String WH = "WH";
-    public final static String IR = "IR";
-    public final static String RISK = "RISK";
+    public final static String TSHH = "TSHH"; // Temperature sum in humid hours
+    public final static String SPH = "SPH"; // Spore producing hour
+    public final static String VAS = "VAS"; // Viable attached spore
+    public final static String WVD = "WVD"; // ??
+    public final static String VRS = "VRS"; // Viable released spores
+    public final static String TSWH = "TSWH"; // ??
+    public final static String WD = "WD"; // Wetness duration
+    public final static String WHS = "WHS"; // Wetness starts (1=yes)
+    public final static String WH = "WH"; // Wet hour
+    public final static String IR = "IR"; // Infection risk (1 = yes), preliminary result
+    public final static String RISK = "RISK"; // Actual risk
     
     // Weather data stored for convenience (putting into result object)
-    public final static String TM = "TM";
-    public final static String UM = "UM";
-    public final static String RR = "RR";
-    public final static String Q0 = "Q0";
-    public final static String BT = "BT";
+    public final static String TM = "TM"; // Mean temperature
+    public final static String UM = "UM"; // Mean relative  humidity (%)
+    public final static String RR = "RR"; // precipitation (mm)
+    public final static String Q0 = "Q0"; // Solar radiation, average W/square meter
+    public final static String BT = "BT"; // Leaf wetness (minutes per hour)