diff --git a/src/Environment/environment.cxx b/src/Environment/environment.cxx
index 9a5755e3d..30354ffd9 100644
--- a/src/Environment/environment.cxx
+++ b/src/Environment/environment.cxx
@@ -211,20 +211,32 @@ FGEnvironment::read (const SGPropertyNode * node)
     maybe_copy_value(this, node, "visibility-m",
                      &FGEnvironment::set_visibility_m);
 
+    maybe_copy_value(this, node, "elevation-ft",
+                     &FGEnvironment::set_elevation_ft);
+
     if (!maybe_copy_value(this, node, "temperature-sea-level-degc",
-                          &FGEnvironment::set_temperature_sea_level_degc))
-        maybe_copy_value(this, node, "temperature-degc",
-                         &FGEnvironment::set_temperature_degc);
+                          &FGEnvironment::set_temperature_sea_level_degc)) {
+        if( maybe_copy_value(this, node, "temperature-degc",
+                         &FGEnvironment::set_temperature_degc)) {
+            _recalc_sl_temperature();
+        }
+    }
 
     if (!maybe_copy_value(this, node, "dewpoint-sea-level-degc",
-                          &FGEnvironment::set_dewpoint_sea_level_degc))
-        maybe_copy_value(this, node, "dewpoint-degc",
-                         &FGEnvironment::set_dewpoint_degc);
+                          &FGEnvironment::set_dewpoint_sea_level_degc)) {
+        if( maybe_copy_value(this, node, "dewpoint-degc",
+                         &FGEnvironment::set_dewpoint_degc)) {
+            _recalc_sl_dewpoint();
+        }
+    }
 
     if (!maybe_copy_value(this, node, "pressure-sea-level-inhg",
-                          &FGEnvironment::set_pressure_sea_level_inhg))
-        maybe_copy_value(this, node, "pressure-inhg",
-                         &FGEnvironment::set_pressure_inhg);
+                          &FGEnvironment::set_pressure_sea_level_inhg)) {
+        if( maybe_copy_value(this, node, "pressure-inhg",
+                         &FGEnvironment::set_pressure_inhg)) {
+            _recalc_sl_pressure();
+        }
+   }
 
     maybe_copy_value(this, node, "wind-from-heading-deg",
                      &FGEnvironment::set_wind_from_heading_deg);
@@ -232,9 +244,6 @@ FGEnvironment::read (const SGPropertyNode * node)
     maybe_copy_value(this, node, "wind-speed-kt",
                      &FGEnvironment::set_wind_speed_kt);
 
-    maybe_copy_value(this, node, "elevation-ft",
-                     &FGEnvironment::set_elevation_ft);
-
     maybe_copy_value(this, node, "turbulence/magnitude-norm",
                      &FGEnvironment::set_turbulence_magnitude_norm);
 
@@ -652,7 +661,7 @@ FGEnvironment::_recalc_sl_temperature ()
   }
 #endif
 
-  if (elevation_ft >= ISA_def[1].height) {
+  if (elevation_ft * atmodel::foot >= ISA_def[1].height) {
     SG_LOG(SG_GENERAL, SG_ALERT, "recalc_sl_temperature: "
         << "valid only in troposphere, not " << elevation_ft);
     return;
diff --git a/src/Environment/environment_ctrl.cxx b/src/Environment/environment_ctrl.cxx
index ea9c9b628..ac870e5e2 100644
--- a/src/Environment/environment_ctrl.cxx
+++ b/src/Environment/environment_ctrl.cxx
@@ -132,7 +132,9 @@ void
 FGInterpolateEnvironmentCtrl::init ()
 {
 	read_table( boundary_n, _boundary_table);
-	read_table( aloft_n, _aloft_table);
+	// pass in a pointer to the environment of the last bondary layer as
+	// a starting point
+	read_table( aloft_n, _aloft_table, &(*(_boundary_table.end()-1))->environment);
 }
 
 void
@@ -142,7 +144,7 @@ FGInterpolateEnvironmentCtrl::reinit ()
 }
 
 void
-FGInterpolateEnvironmentCtrl::read_table (const SGPropertyNode * node, vector<bucket *> &table)
+FGInterpolateEnvironmentCtrl::read_table (const SGPropertyNode * node, vector<bucket *> &table, FGEnvironment * parent )
 {
 	double last_altitude_ft = 0.0;
 	double sort_required = false;
@@ -163,8 +165,11 @@ FGInterpolateEnvironmentCtrl::read_table (const SGPropertyNode * node, vector<bu
 				b = new bucket;
 				table.push_back(b);
 			}
+			if (i == 0 && parent != NULL )
+				b->environment.copy( *parent );
 			if (i > 0)
 				b->environment.copy(table[i-1]->environment);
+			
 			b->environment.read(child);
 			b->altitude_ft = b->environment.get_elevation_ft();
 
diff --git a/src/Environment/environment_ctrl.hxx b/src/Environment/environment_ctrl.hxx
index aec1442cb..1f81c0259 100644
--- a/src/Environment/environment_ctrl.hxx
+++ b/src/Environment/environment_ctrl.hxx
@@ -101,7 +101,7 @@ private:
 		static bool lessThan(bucket *a, bucket *b);
 	};
 
-	void read_table (const SGPropertyNode * node, std::vector<bucket *> &table);
+	void read_table (const SGPropertyNode * node, std::vector<bucket *> &table, FGEnvironment * parent = NULL );
 	void do_interpolate (std::vector<bucket *> &table, double altitude_ft,
 						 FGEnvironment * environment);