mazzy1026 asks why on some murky/hazy warm days the haze (non-technical sense) doesn't burn off in the afternoon.
The answer is the temperature inversion with height. At some point (say 3k ft), the rate at which the air becomes colder with height is lower than the rate at which a parcel of air, heated by the ground, loses heat as it rises.
This means that the warm air rising (or thermal, as we glider pilots say), stops at the inversion. So all the haze remains trapped under the inversion and just recirculates.
If the ground temperature rises high enough, the thermals "break down" the inversion which then disappears. Heated air rises above it to the next inversion, or until it forms cumulus and thereafter runs out of energy at the cloud tops.
If this happens the hazy air below the inversion mixes with the clean air above, and the haze " burns off".
If it never gets hot enough for this to happen (and of course, the haze cuts down solar heating to the ground), the haze remains all day.
A helpful introduction to temperature soundings and forecasting is at:
http://www.itadvice.co.uk/weatherjac...t-snds-01.html