The sun! The wine! The attractions!

#happiness in Napa. (Justin Sullivan/Getty Images)

It's enough to make you go, "OMG! I <3 <3 <3 NorCal! LOL"

Tweet that, and you could help your community earn recognition as one of America's happiest cities. That's how it worked with Napa, which was called the happiest city in America in a new study. It's at least the second Northern California city to be endowed with that particular crown in recent years: in 2009, San Francisco was the only American metropolis that appeared on a Forbes list of the world's happiest cities. The marketing firm Space Chimp Media used the Forbes list to create an eye-catching infographic that made its way around the Internet this January.

Here's a look at how each city earned its "happiest" designation:

NAPA

[ad fullwidth]

Researchers at the University of Vermont named Napa the happiest city in the country after going through 10 million Tweets that were posted in 2011 and tagged to 373 U.S. urban areas. They compared the language in those Tweets to a list of words ranked for "happiness." That list of more than 10,000 words was created for another study; it ranks "laughter," "happiness," "love," "happy" and "laughed" as the five happiest words, and "terrorist," "suicide," "rape," "terrorism" and "murder" as the five least happy words.

Compared to Tweets tagged to other cities, those tagged to Napa were more likely to feature words that appear higher on the happy list, including:

lol
like
haha
me
funny

Tweets tagged to Napa also were less likely to include words that were lower on the list, such as:

hate
bad
damn
not
hell

You can read a .PDF of the Vermont research here. It notes that income may play a role in determining which cities have happier Tweets:

"Happiness within the U.S. was found to correlate strongly with wealth, showing largest positive correlation with household income and strongest negative correlation with poverty amongst the census data sets used."

The phrase "drunk Tweeting after wine tasting" does not appear in the study. We checked.

SAN FRANCISCO

San Francisco was the happiest American city on the 2009 Forbes list of the world's happiest cities. Overall, it came in at No. 7 in the world, ranking between Rome and Madrid. The Forbes list was based on the Anholt-Gfk Roper City Brands Index, which used online interviews with 10,000 respondents to measure the perception of municipalities in six areas:

Presence: the city's international status
Place: the physical aspects of a city, including climate and architecture
Pre-requisites: the basics of city life, such as schools and transportation
People: the attitudes of city residents
Pulse: whether or not the city offers interesting and new activities
Potential: the economic and educational opportunities in a city

The perceptions of cities in those areas are used to calculate a total index score. Forbes didn't report the index scores for each city, but here is how it described San Francisco:

The lone American metropolis, San Francisco makes the list because it's perceived by foreigners as the "most fun" of America's major cities. "It's associated with gay pride," says (policy advisor and index founder Simon) Anholt. "That's a happy image unless you're a raging homophobe."

The perception of San Francisco as a gay-friendly city helped it earn the title America's happiest city. (Terri Hodges/Flickr)

Of course, the quality of San Francisco gay life isn't the only reason to think it's the country's happiest city. (And it's worth noting that San Francisco didn't even make The Advocate's list of the gayest cities in America in 2012.) The Space Chimp Media infographic notes that the city has plenty of interesting attractions, including 203 shopping centers and 64 cultural venues.

So if you like shopping, you're interested in diversity and culture and you're gay, you might be happy in San Francisco.

And if you're already a San Francisco or Napa resident, you should count your blessings. You might've ended up in Sacramento, Stockton, Merced, Bakersfield, Vallejo or Modesto - all of which appeared on Forbes' list of America's most miserable cities in 2012.

Here's the Space Chimp Media infographic:

Happiest CitiesHappiest Cities

Why San Francisco and Napa Have Been Ranked as the Happiest Cities in America