The dew point depression (T-Td) is the difference between the temperature and dew point temperature at a certain height in the atmosphere.
The smaller the difference, the more moisture there is, and the higher the relative humidity. In the lower troposphere, more moisture (small dew point depression) results in lower cloud bases and is also important to severe thunderstorms. Conversely, instability is increased when there is a mid-level dry layer (large dew point depression) known as a "dry punch", which is favorable for convection if the lower layer is buoyant.
As it measures moisture content in the atmosphere, the dew point depression is also an important indicator in agricultural and forest meteorology, particularly in predicting wildfires.
Famous quotes containing the words dew, point and/or depression:
“Enjoy the honey-heavy dew of slumber.
Thou hast no figures, nor no fantasies,
Which busy care draws in the brains of men;
Therefore thou sleep’st so sound.”
—William Shakespeare (1564–1616)
“Of all illusions in the world, the most universally received is the concern for reputation and glory, which we espouse even to the point of giving up riches, rest, life, and health, which are effectual and substantial goods, to follow that vain phantom and mere sound that has neither body nor substance.”
—Michel de Montaigne (1533–1592)
“Someone is always at my elbow reminding me that I am the grand-daughter of slaves. It fails to register depression with me. Slavery is sixty years in the past. The operation was successful and the patient is doing well, thank you. The terrible struggle that made me an American out of a potential slave said “On the line!” The Reconstruction said “Go!” I am off to a flying start and I must not halt in the stretch to look behind and weep.”
—Zora Neale Hurston (1891–1960)