Its intensity varies directly with the strength of convection. 2.4 Advection The effects of radiation vary considerably depending on the type of surface, but also with latitude and the season. Thus the upper-air temperature profile must constantly be updated. Surface and upper-air charts are used for this purpose, on which lines are drawn to delimit areas at the same temperature every 4 or 5 degrees. These lines are called isotherms.
Advection means that there is horizontal movement of an air mass toward a colder or warmer region.
It indicates warming or cooling. The steeper the horizontal thermal gradient with a strong wind reaching its maximum speed as it blows parallel to the gradient, the greater the advection. Behind the cold front, in blue, is a west wind pushing the isotherms eastward. Figure 2-2 Isotherms and lapse rate, on an 850 hPa chart. The purple arrow indicates the lapse rate.