Geopotential in 850 hPa (solid, black lines) and Temperature advection in K/6h (colored lines)
The map "T-Adv 850" shows the advection of cold or warm air at 850 hPa
level. Negative values indicate cold advection, while positive values
indicate warm air advection. Advection of warm or cold air causes the
geopotential height to respectively rise or drop, producing vertical rising
and sinking motion of air. There is, however, not a direct relationship
between temperature advection and resultant vertical motion in the
atmosphere since other lifting and sinking mechanisms can complicate the
picture, e.g. vorticity advection (see "V-Adv maps").
In weather forecasting, temperature advection maps are often used to locate
the postion of wam and cold fronts. Cold advection is common behind cold
fronts, while warm advection is common behind warm fronts and ahead of cold
fronts. Higher in the atmosphere temperature advection is getting less
pronounced, as horizontal much more uniform in temperature and the flow is
more zonal.