Notes on Tephigram
A tephigram is a graphical representation of observations of pressure, temperature and humidity made in a vertical sounding of the atmosphere. Vertical soundings are made using an instrument called a radiosonde, which contains pressure, temperature and humidity sensors and which is launched into the atmosphere attached to a balloon.
The tephigram contains a set of process curves which are used to describe various processes in the atmosphere. These lines include:
On the tephigram there are two kinds of information represented:
The environment curves which describes the structure of the atmosphere. These are Temperature (Red) and Dew Point (Green)
The process curves which describes what happens to a parcel of air undergoing a particular type of process. (eg. Adiabatic process).
In addition, on the right hand side are wind direction and speed and heights at the standard levels. Wind is shown in wind-arrow format with the head of the pointing to where the wind is going and the strength given by the feathers – a long feather is 10kts, a short feather 5knots and a triangle 50kts. Add the feathers to get the speed.
Tephigrams can be used by the forecaster for the following purposes:
– to determine moisture levels in the atmosphere
– cloud heights
– to predict levels of convective activity in the atmosphere
– forecast maximum and minimum temperatures
– forecast fog formation and fog clearance
– detect the presence and height of inversions