Natural gas made a significant move in the futures market on Monday, surging more than 8% after the contracts for July delivery closed at $4.182 per 1,000 cubic feet.

What's interesting about the move in nat gas is that it ran up significantly even as the entire market fell and crude oil dropped to $70.62 a barrel. Commodities were clearly leading the markets lower on Monday, and a strong dollar might have also helped to push equities down. But the strength in nat gas was seen as a surprise to many market players.

The reason for nat gas's strength is hard to pin down. Some investors believe that nat gas is just too cheap, as demonstrated by the divergence between the spread of rising crude oil and left-for-dead natural gas prices.

Just take a look at the two ETFs for these commodities, U.S. Oil Trust ( USO) and U.S. Natural Gas Trust ( UNG), to get a good idea of how out of whack the spread is. The current spread for a barrel of crude and 1,000 cubic feet of natural gas is around 18-to-1, vs. the historical average of 10.

This gigantic spread, which is actually the largest ever in history, might be prompting some investors to short crude and go long natural gas to try to capture some gains if that spread comes in. The volume on the U.S. Natural Gas Fund recently would suggest that some large investors are starting to warm up to this trade idea. On July 11, more than 96 million shares traded as the ETF closed up close to $1, vs. the average daily volume of only 22 million shares.

Jim Cramer is also noticing the trend, and he's starting to buy a nat gas stock, Devon ( DVN), which could be a big beneficiary of this potential move. Cramer thinks names like Southwestern ( SWN) and Chesapeake Energy ( CHK) could also be great plays because both companies have big exposure to nat gas.

If nat gas is finally starting to heat up, then how should investors look to play this space? Let's take a look at a few nat gas stocks that look interesting based off of their chart patterns.

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