The main chart is wind speed and direction by height. Below is a short guide to the Solar and Lift strips under the cloud bands.

Solar and lift

Solar is model shortwave radiation reaching the surface. Dark means weak heating (night or heavy cloud); bright means strong sunshine.

Lift is a thermal-updraft scale in m/s, using the same parcel physics as the Parcel buoyancy tab.

Mixing depth (when the model does not supply boundary-layer height) uses the same estimate as the Parcel tab’s BL top (est.): the Parcel buoyancy field is oversampled in time and height, smoothed with a vertical box blur, then LCL from 3-hour smoothed 2 m temperature and humidity is combined with the highest altitude that still has smoothed buoyancy > 0. If that column has no positive smoothed buoyancy, Lift is forced to 0.

Deardorff w* (convective velocity scale, consistent with Canada RASP) is used when the model provides surface sensible and latent heat fluxes (GFS, HRRR, and most ERA5-based runs). Where fluxes are unavailable (HRDPS, ICON, some ECMWF runs), Lift falls back to √(CAPE / 100), which gives roughly 1 m/s at 100 J/kg and 2 m/s at 400 J/kg.

Atmospheric stability (lapse rate)

Background colour shows the local lapse rate (°C per 1,000 ft) between adjacent model levels — identical to the canadarasp windgram colour scale.

DALR reference

The Dry Adiabatic Lapse Rate is −3 °C/1000 ft (−9.8 °C/km). Air below that boundary is absolutely unstable and thermals will fire freely.

How it works

A surface air parcel is lifted from the takeoff elevation. It cools at the Dry Adiabatic Lapse Rate (9.8 °C/km) until it reaches the LCL (Lifting Condensation Level — where cloud forms), then at the slower Saturated Adiabatic Lapse Rate above. Colour shows T_parcel − T_environment at each altitude: positive (warm colours) means the thermal is still buoyant and rising at that height; negative (cool colours) means it has been capped.

Reference lines

White line — LCL (cloud base): height at which the rising parcel saturates. Below it thermals are dry; above it condensation releases latent heat and thermals can climb further.

Black line — BL top: from the model’s boundary-layer height when the primary run provides it (e.g. HRDPS ~1 km). On HRDPS ~2.5 km the chart uses BL top (est.): mixing depth from the same pipeline as the coloured field — sub-hour and sub-layer oversampling, vertical box blur, then the highest smoothed buoyancy > 0 (averaged across sub-hour columns), combined with LCL from 3-hour smoothed 2 m temperature and humidity (minimum 80 m AGL to draw). The Wind tab Lift strip uses the same smoothed mixing depth when the model does not supply BLH.

Environmental air temperature

Colour shows model air temperature (°C) at each altitude, using the same pressure levels as the wind profile. Values are oversampled in time and height and smoothed with a vertical box blur (same pipeline as the Parcel buoyancy tab) so small-scale layer noise is softened.

Between the ground and the lowest model level, temperature is blended from 2 m temperature to the first isobaric level. Colours are in 5 °C steps from −30 to +30 °C (values outside that use the end colours). Blue is cold; red is warm.

Clouds tab

The main plot uses model cloud cover % at each pressure level: dark = clear air, light = thick cloud. Precipitation and the low / mid / high rows apply on every tab. Below those rows, the Solar strip (shortwave radiation — same scale as on the Wind tab) is shown here too.

Low / mid / high rows

Total cloud fraction in three altitude layers. Darker = more cloud.