Psychrometric state and crop verdicts.
An outdoor air state, graded against a crop's own climate recipe.
The queried state
Dry-bulb 43 °C at 12 % relative humidity.
The air state
| Dry-bulb temperature | 43.0 °C |
|---|---|
| Relative humidity | 12.0 % |
| Humidity ratio | 0.0064 kg/kg |
| Vapour pressure | 1038 Pa |
| Dew point | 7.5 °C |
| Wet bulb | 20.9 °C |
| Specific enthalpy | 59871 J/kg |
| Air vapour-pressure deficit | 7611 Pa |
| Density | 1.112 kg/m³ |
| Pressure | 101325 Pa |
The psychrometric chart
The crop recipe — LET-BUTTER
Day climate
| Temperature | 21.85 °C (range 21–22.7) |
|---|---|
| Relative humidity | 70 % (range 60–80) |
| Vapour-pressure deficit | 0.7861953886352817 kPa (range 0.5241302590901875–1.0482605181803755) |
| Daily light integral | 12.35 mol/m²/d (range 11.5–13.2) |
| Photoperiod | 16 h (range 14–17) |
| CO₂ | 1000–1100 ppm |
| Root-zone temperature | No published value. The crop record states none. (°C) |
Night climate
| Temperature | Held for engineering review — not published. (°C) |
|---|---|
| Relative humidity | Held for engineering review — not published. (%) |
| Vapour-pressure deficit | Held for engineering review — not published. (kPa) |
| Daily light integral | Held for engineering review — not published. (mol/m²/d) |
| Photoperiod | Held for engineering review — not published. (h) |
| CO₂ | Held for engineering review — not published. (ppm) |
| Root-zone temperature | Held for engineering review — not published. (°C) |
Stress limits
| Hard low temperature | Held for engineering review — not published. (°C) |
|---|---|
| Hard high temperature | Held for engineering review — not published. (°C) |
| VPD alert | Held for engineering review — not published. (kPa) |
| Disease humidity alert | Held for engineering review — not published. (%) |
| Dew-point margin | Held for engineering review — not published. (°C) |
| High-DLI alert | Held for engineering review — not published. (mol/m²/d) |
Irrigation
| Irrigation pH | 5.5–6 pH |
|---|---|
| Irrigation EC | 1.6–1.8 mS/cm |
| Drain fraction | No published value. The crop record states none. (%) |
| Dosing capacity | No published value. The crop record states none. (L/m²/h) |
| Daily water use | No published value. The crop record states none. (L/m²/d) |
Transpiration
| Mature leaf-area index | Held for engineering review — not published. (m²/m²) |
|---|---|
| Light extinction coefficient | Held for engineering review — not published. (-) |
| Minimum stomatal resistance | Held for engineering review — not published. (s/m) |
| Daily transpiration | Held for engineering review — not published. (kg/m²/d) |
| Peak transpiration | Held for engineering review — not published. (kg/m²/h) |
Verdicts
Day — graded at full light, 200 W/m², the engine's own day threshold provisional
Temperature — risk (damage_risk). Air temperature lies beyond the tolerance limit the crop record states by more than the stress margin. Tissue damage and loss of the crop follow while the state holds. Fog cools by evaporating water into the air the crop stands in, so the temperature falls and the humidity rises together, down to the margin that keeps water off the crop.
Vapour-pressure deficit — tolerance (outside_dry). Leaf-level vapour-pressure deficit runs above the recipe envelope. The crop transpires faster than its recipe intends; stomata close to protect the plant and assimilation carries a penalty while the state holds. Fog cools by evaporating water into the air the crop stands in, so the temperature falls and the humidity rises together, down to the margin that keeps water off the crop.
Condensation margin — comfort (comfortable). The coldest plant surface stays clear of the dew point of its air. Water stays off the crop at this state.
Night — graded with no sun
Temperature — risk (damage_risk). Air temperature lies beyond the tolerance limit the crop record states by more than the stress margin. Tissue damage and loss of the crop follow while the state holds. A semi-closed greenhouse holds a setpoint mechanically rather than evaporatively, and dries the air by controlled condensation to the margin the crop record states, keeping enriched air where the crop is.
Vapour-pressure deficit — tolerance (outside_dry). Leaf-level vapour-pressure deficit runs above the recipe envelope. The crop transpires faster than its recipe intends; stomata close to protect the plant and assimilation carries a penalty while the state holds. A semi-closed greenhouse holds a setpoint mechanically rather than evaporatively, and dries the air by controlled condensation to the margin the crop record states, keeping enriched air where the crop is.
Condensation margin — comfort (comfortable). The coldest plant surface stays clear of the dew point of its air. Water stays off the crop at this state.
Worked examples
Riyadh — July
Outdoor: 43 °C at 12 % by day, 31 °C at 22 % by night; day length 13.6 h.
| Tiers | Day °C | Night °C | 24 h mean °C | Grade | Class | Next rung | Link |
|---|---|---|---|---|---|---|---|
| vent, fog | 23.9 | 19.8 | 22.16 | inside | comfort | none | open |
| Air temperature sits outside the recipe band and within the grading envelope. The envelope is about as wide as the leaf model resolves, so the state reads as comfort rather than as a departure from target. | |||||||
| vent | 43.0 | 31.0 | 37.80 | above | risk | fog | open |
| Air temperature lies beyond the tolerance limit the crop record states by more than the stress margin. Tissue damage and loss of the crop follow while the state holds. Fog cools by evaporating water into the air the crop stands in, so the temperature falls and the humidity rises together, down to the margin that keeps water off the crop. | |||||||
| baseline | 76.7 | 31.0 | 56.91 | above | risk | fog | open |
| Air temperature lies beyond the tolerance limit the crop record states by more than the stress margin. Tissue damage and loss of the crop follow while the state holds. Fog cools by evaporating water into the air the crop stands in, so the temperature falls and the humidity rises together, down to the margin that keeps water off the crop. | |||||||
Dubai — August
Outdoor: 41 °C at 45 % by day, 33 °C at 70 % by night; day length 13.4 h.
| Tiers | Day °C | Night °C | 24 h mean °C | Grade | Class | Next rung | Link |
|---|---|---|---|---|---|---|---|
| vent, fog | 32.9 | 31.2 | 32.17 | above | stress | semi_closed | open |
| Air temperature has passed the tolerance limit the crop record states and stays within the stress margin beyond it. The crop survives; yield and quality carry a direct penalty for as long as the state holds. A semi-closed greenhouse holds a setpoint mechanically rather than evaporatively, and dries the air by controlled condensation to the margin the crop record states, keeping enriched air where the crop is. | |||||||
| semi_closed | 21.0 | 18.5 | 19.90 | inside | comfort | none | open |
| Air temperature sits inside the blended recipe band for this radiation level. The crop holds its target temperature. | |||||||
| baseline | 72.8 | 33.0 | 55.20 | above | risk | semi_closed | open |
| Air temperature lies beyond the tolerance limit the crop record states by more than the stress margin. Tissue damage and loss of the crop follow while the state holds. A semi-closed greenhouse holds a setpoint mechanically rather than evaporatively, and dries the air by controlled condensation to the margin the crop record states, keeping enriched air where the crop is. | |||||||
Beja — July
Outdoor: 36 °C at 25 % by day, 18 °C at 60 % by night; day length 14.6 h.
| Tiers | Day °C | Night °C | 24 h mean °C | Grade | Class | Next rung | Link |
|---|---|---|---|---|---|---|---|
| vent, fog | 23.9 | 16.4 | 20.97 | inside | comfort | none | open |
| Air temperature sits inside the blended recipe band for this radiation level. The crop holds its target temperature. | |||||||
| baseline | 67.8 | 18.0 | 48.27 | above | risk | fog | open |
| Air temperature lies beyond the tolerance limit the crop record states by more than the stress margin. Tissue damage and loss of the crop follow while the state holds. Fog cools by evaporating water into the air the crop stands in, so the temperature falls and the humidity rises together, down to the margin that keeps water off the crop. | |||||||
Naaldwijk — July
Outdoor: 22 °C at 70 % by day, 15 °C at 85 % by night; day length 16.3 h.
| Tiers | Day °C | Night °C | 24 h mean °C | Grade | Class | Next rung | Link |
|---|---|---|---|---|---|---|---|
| vent | 25.0 | 15.0 | 21.79 | inside | comfort | none | open |
| Air temperature sits inside the blended recipe band for this radiation level. The crop holds its target temperature. | |||||||
| baseline | 42.9 | 15.0 | 33.96 | above | stress | vent | open |
| Air temperature has passed the tolerance limit the crop record states and stays within the stress margin beyond it. The crop survives; yield and quality carry a direct penalty for as long as the state holds. Ventilation moves the greenhouse toward the outdoor air, which is as far as opening the vents can take it. | |||||||
Provenance
Computed by the DGH Climate Engine, version 0.2.0.
Two layers, stated separately: the psychrometric-core layer is validated; the greenhouse-model layer is design-stage.
Licence: Apache-2.0, covering software-implementation.
Attribution: DutchGreenhouses® — DGH Climate Engine
Citation: DutchGreenhouses B.V. (2026). DGH Climate Engine v0.2.0. Apache-2.0.
Sources: plant_empowerment, bakker_1995, ashrae_2017, dgh_crop_model_db.
Methodology · Canonical link for this view
Indicative, design-stage. Engineering confirms.