You are given a passage. You need to construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) its answer is the whole paragraph. Avoid creating questions that can be answered correctly without actually understanding the paragraph.

The fog that develops in the Central Valley is called Radiation Fog. The page listed 1st as a source states:

"Climatologically important conditions for radiation-fog development in the Central Valley include cool 1600 LST surface temperatures, moisture availability as reflected by 1600 LST dewpoint temperatures, early evening surface cooling trends, the rapidity with which mean relative humidity reaches 90%, and the presence of cool, dry air aloft (700500 hPa)."

Go to this page:
http://www.islandnet.com/~see/weather/almanac/arc2002/alm02sep.htm
and find the header "Radiaton Fog" about 1/3 down the page to see a very nice explanation of how Radiation fog forms.
Why is it so Foggy in the Central Valley of California?