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:
“How many women ... waste life away the prey of discontent, who might have practised as physicians, regulated a farm, managed a shop, and stood erect, supported by their own industry, instead of hanging their heads surcharged with the dew of sensibility, that consumes the beauty to which it at first gave lustre ...”
—Mary Wollstonecraft (1759–1797)
“What’s the point of fighting the dollars
when all you need is a warm bed?
When the dog barks you let him in.
All we need is someone to let us in.
And one other thing:
to consider the lilies in the field.”
—Anne Sexton (1928–1974)
“I realized how for all of us who came of age in the late sixties and early seventies the war was a defining experience. You went or you didn’t, but the fact of it and the decisions it forced us to make marked us for the rest of our lives, just as the depression and World War II had marked my parents.”
—Linda Grant (b. 1949)