Skew-T diagram

large, multi-colored
(brown, green, and black) chart with numerous scales and

graphs superimposed upon each other.

intervals. Pressure-value labels are printed at both ends and in

the center of the chart for each 50-mb interval.

lower left to the upper right with the spacing equal

throughout the diagram. Isotherms are labeled for 5°C intervals, with alternate 10°C temperature bands tinted green. A Fahrenheit temperature scale is printed along the bottom edge of the chart to coincide with the appropriate Celsius isotherms.

are the slightly curved, solid, brown lines that slope from

the lower right to the upper left. They indicate the rate of temperature change in a parcel of dry air which is rising or descending adiabatically when no change of state is occurring with water; e.g., no moisture is changing from vapor to liquid or solid, or solid to liquid to vapor, i.e. with no loss or gain of heat by the parcel.

are the slightly curved, solid, green lines sloping from the

lower right to the upper left, except those on the extreme right. They indicate the temperature change experienced by a saturated parcel of air rising pseudo-adiabatically through the atmosphere. Pseudo-adiabatic means all the condensed water vapor is assumed to fall out (precipitate) immediately as the air rises.

dashed, green lines sloping from the lower left to the

upper right. Saturation mixing-ratio lines are labeled in parts of water vapor per 1000 parts of dry air (grams/kilogram). Values are printed in green between the 1000-mb line and the 950-mb line.

important isopleths are straight rather than curved;
the angle between the

adiabats and isotherms is large enough to facilitate estimates of the stability;
the ratio of area on the chart to thermodynamic energy is the same over the whole diagram;
the isobars are plotted to a logarithmic scale and pressure in the atmosphere decreases nearly logarithmically with height;
an entire sounding to levels in the stratosphere can be plotted on one chart.

the plotting of radiosonde soundings, which give a vertical profile

of the temperature and dew point through the atmosphere above a certain point on the ground. The isopleths on the diagram can then be used to simplify many tedious calculations involved, which were previously performed by hand or not at all.