diff --git a/src/services/environment.py b/src/services/environment.py
index 991c865..3330869 100644
--- a/src/services/environment.py
+++ b/src/services/environment.py
@@ -28,13 +28,18 @@ def from_env_model(cls, env: EnvironmentModel) -> Self:
             elevation=env.elevation,
             date=env.date,
         )
+        # RocketPy guards pressure/temperature against None but NOT wind, so
+        # a custom_atmosphere with wind_u/wind_v left unset raises
+        # "'NoneType' object has no attribute 'shape'". Default missing wind
+        # to 0 (only None is replaced — real 0.0 values and wind profiles pass
+        # through).
         rocketpy_env.set_atmospheric_model(
             type=env.atmospheric_model_type,
             file=env.atmospheric_model_file,
             pressure=env.pressure,
             temperature=env.temperature,
-            wind_u=env.wind_u,
-            wind_v=env.wind_v,
+            wind_u=env.wind_u if env.wind_u is not None else 0.0,
+            wind_v=env.wind_v if env.wind_v is not None else 0.0,
         )
         return cls(environment=rocketpy_env)
 
diff --git a/tests/unit/test_services/test_environment_service.py b/tests/unit/test_services/test_environment_service.py
new file mode 100644
index 0000000..9f4ce9e
--- /dev/null
+++ b/tests/unit/test_services/test_environment_service.py
@@ -0,0 +1,95 @@
+from src.models.environment import EnvironmentModel
+from src.services.environment import EnvironmentService
+
+
+def test_from_env_model_custom_atmosphere_default_wind_none():
+    env_model = EnvironmentModel(
+        latitude=0.0,
+        longitude=0.0,
+        elevation=0.0,
+        atmospheric_model_type='custom_atmosphere',
+        pressure=101325.0,
+        temperature=288.15,
+        wind_u=None,
+        wind_v=None,
+    )
+    service = EnvironmentService.from_env_model(env_model)
+    assert service.environment.wind_velocity_x(0) == 0.0
+    assert service.environment.wind_velocity_y(0) == 0.0
+
+
+def test_from_env_model_custom_atmosphere_one_wind_component_none():
+    env_model_u_set = EnvironmentModel(
+        latitude=0.0,
+        longitude=0.0,
+        elevation=0.0,
+        atmospheric_model_type='custom_atmosphere',
+        pressure=101325.0,
+        temperature=288.15,
+        wind_u=5.0,
+        wind_v=None,
+    )
+    service_u = EnvironmentService.from_env_model(env_model_u_set)
+    assert service_u.environment.wind_velocity_x(0) == 5.0
+    assert service_u.environment.wind_velocity_y(0) == 0.0
+
+    env_model_v_set = EnvironmentModel(
+        latitude=0.0,
+        longitude=0.0,
+        elevation=0.0,
+        atmospheric_model_type='custom_atmosphere',
+        pressure=101325.0,
+        temperature=288.15,
+        wind_u=None,
+        wind_v=3.0,
+    )
+    service_v = EnvironmentService.from_env_model(env_model_v_set)
+    assert service_v.environment.wind_velocity_x(0) == 0.0
+    assert service_v.environment.wind_velocity_y(0) == 3.0
+
+
+def test_from_env_model_custom_atmosphere_explicit_zero_wind():
+    env_model = EnvironmentModel(
+        latitude=0.0,
+        longitude=0.0,
+        elevation=0.0,
+        atmospheric_model_type='custom_atmosphere',
+        pressure=101325.0,
+        temperature=288.15,
+        wind_u=0.0,
+        wind_v=0.0,
+    )
+    service = EnvironmentService.from_env_model(env_model)
+    assert service.environment.wind_velocity_x(0) == 0.0
+    assert service.environment.wind_velocity_y(0) == 0.0
+
+
+def test_from_env_model_custom_atmosphere_wind_profile_list():
+    wind_u_profile = [(0.0, 2.0), (1000.0, 10.0)]
+    wind_v_profile = [(0.0, 1.0), (1000.0, 5.0)]
+    env_model = EnvironmentModel(
+        latitude=0.0,
+        longitude=0.0,
+        elevation=0.0,
+        atmospheric_model_type='custom_atmosphere',
+        pressure=101325.0,
+        temperature=288.15,
+        wind_u=wind_u_profile,
+        wind_v=wind_v_profile,
+    )
+    service = EnvironmentService.from_env_model(env_model)
+    assert service.environment.wind_velocity_x(0) == 2.0
+    assert service.environment.wind_velocity_x(1000) == 10.0
+    assert service.environment.wind_velocity_y(0) == 1.0
+    assert service.environment.wind_velocity_y(1000) == 5.0
+
+
+def test_from_env_model_standard_atmosphere():
+    env_model = EnvironmentModel(
+        latitude=0.0,
+        longitude=0.0,
+        elevation=0.0,
+        atmospheric_model_type='standard_atmosphere',
+    )
+    service = EnvironmentService.from_env_model(env_model)
+    assert service.environment is not None