Difference Between Frost and Freeze

South Florida had a Freeze in January and many gardeners lost plants. I didn't lose anything that I cried over. Here's the run-down.

Yesterday and today, we had a wind chill warning, freeze warning, and red flag warning. It was 51 degrees on my porch at 8am. At around 6am, it was 47 degrees.

I took this little tomato/basil pot inside. I also moved the new miracle plant inside the garage. I wasn't really that concerned, but these are the two plants I've been putting a lot of energy into lately and I didn't want to take the chance.

So, what is the difference between a frost, freeze, wind chill, and frost/freeze warning, and what is a red flag warning? Are four warning levels of cold really needed? Is this system like the hurricane system...do we need to remember the difference between a watch and a warning?

Considering, Florida's agriculture industry's total economic impact is $59 billion ('08 UF study), I think we really do need a sophisticated weather warnng system.

I've just searched for 30 minutes to find actual definitions of what these warnings mean. I found the definitions on the nat weather service website, but they are not specific and don't contain degrees. They also say to check with individual states because terms vary by state. I'll look it up again later. How frustrating. Here are a few pieces of info I found:

A freeze warning is issued for 3 or more hours of temperatures between 27 and 32 over a widespread area. Residents should cover or move indoors any cold sensitive plants...and bring pets indoors.

A red flag warning means that critical fire weather conditions are either occurring now...or will shortly.

A wind chill advisory means that very cold air and gusty winds will combine to generate low wind chills.

A definition: http://www.weather.gov/glossary/index.php?word=freeze
A good table: http://www.ces.ncsu.edu/depts/hort/hil/hil-705.html