diff --git a/coefficients.py b/coefficients.py
index 7f82546..8a78689 100644
--- a/coefficients.py
+++ b/coefficients.py
@@ -21,3 +21,8 @@ RSI_HORIZONTAL = 0.13
 RSI_UPWARD = 0.10
 RSI_DOWNWARD = 0.17
 RSE = 0.04
+
+# Air properties
+RHO_AIR = 1.2       # kg/m³
+CP_AIR = 1005       # J/(kg·K)
+RHO_CP_AIR = RHO_AIR * CP_AIR  # J/(m³·K), volumetric heat capacity