Soaring weather - in plain English.

Above Ground Level - altitude measured relative to the terrain directly beneath.

AGL is the altitude reference a pilot actually feels. A cloudbase of 5,000 ft AGL means 5,000 ft above the ground beneath you, not above sea level. Convek reports ceilings and cloudbase in AGL wherever it makes sense for pilots.

The lowest part of the atmosphere, where surface heating drives turbulent mixing.

The boundary layer (or planetary boundary layer, PBL) is the layer of air directly in contact with the ground. On a sunny day it grows from a thin pre-dawn layer to a deep convective layer as the sun heats the surface. Thermal flying happens inside the boundary layer - its depth is one of the most important variables for soaring.

The altitude at which cumulus cloud forms - the top of the thermalling layer on a cloud day.

When a thermal rises high enough that its moisture condenses, you see a cumulus cloud. Its base is the cloudbase. Convek reports cloudbase both in metres MSL and feet AGL.

A line where two airmasses meet, often producing strong lift along a narrow feature.

Convergence happens where surface flows meet - sea breeze fronts, valley wind confluences, airmass boundaries. Along the line, air is forced upward, producing stretches of continuous lift that XC pilots use as routes.

Whether conditions support cumulus formation, and how strongly.

A qualitative measure of whether thermals will reach condensation and produce cumulus clouds. Blue days have no cumulus potential; soarable cloud days have moderate potential; overdevelopment happens when potential is too high.

A single label summarising overall soaring quality on a given day.

Convek's day_rating collapses thermal strength, ceiling, wind, and cumulus conditions into one label: poor, marginal, fair, good, or excellent. Useful for go / no-go decisions and for sorting days across a week.

The effective thermalling ceiling, capped for realistic glider performance.

hglider_agl_m is the height to which a glider can realistically climb in thermals on the day, given PBL depth, moisture, and glider performance assumptions. It is usually lower than raw boundary-layer height.

Lifted Condensation Level - the altitude at which a rising parcel of air becomes saturated.

The LCL is the theoretical altitude at which a rising parcel, lifted from the surface, cools enough for its moisture to condense. It's the physics foundation of cloudbase.

Mean Sea Level - altitude measured relative to sea level.

MSL is the altitude reference used by aviation charts and ATC. Convek reports both MSL and AGL where each makes sense.

When cumulus clouds grow into shower or storm cells, shutting down thermals.

OD happens when cumulus potential is too strong: clouds grow vertically, shade the ground, precipitate, and stabilise the airmass. Pilots watch OD risk closely on marginal days.

Planetary Boundary Layer - see Boundary layer.

Same concept as boundary layer. Model output typically labels it PBL or boundary_layer_height.

Regional Atmospheric Soaring Prediction - a convention for post-processed soaring forecasts.

RASP is a set of derived fields (thermal strength, glider ceiling, trigger temperature, etc.) computed from mesoscale model output. Convek produces RASP-style fields from WRF.

A vertical profile of the atmosphere - temperature, dewpoint, wind by altitude.

A sounding plots atmospheric state against altitude. Real soundings come from radiosondes; forecast soundings are produced by models. They are essential for diagnosing thermal depth, inversions, and shear.

A rising column of warm air - the lift soaring pilots climb in.

Thermals form when surface heating creates a layer of air warmer than its surroundings, which becomes buoyant and rises. They power cross-country flight for gliders, paragliders, and hang gliders.

The surface temperature at which thermals start firing.

The trigger temperature is the threshold at which surface air becomes buoyant enough to rise through the capping inversion. When surface temperature exceeds trigger, thermals start; before that, the sky is dead.

A measure of convective updraft velocity, in m/s.

Wstar (w*) is a scaling velocity for the convective boundary layer, derived from surface heat flux and PBL depth. It approximates average thermal strength. Higher wstar = stronger thermals.

Weather Research and Forecasting - the model Convek runs.

WRF is an open-source mesoscale atmospheric model developed at NCAR. Convek runs WRF at 4 km over the UK, four times a day, as the engine behind every forecast the API serves.