Here is a histogram of the 30 minute trading range for the ES contract (day session). This type of intraday range or volatility profile is pretty standard. http://goo.gl/nWv1q
OP, how many of the "patterns" you've been asking about recently did you recognize during your specified "lunch time"?
So "chop" refers to the range of the individual bars rather than the range of the ES? Hmm, we have different definitions of chop, so I see why I disagreed about lunchtime "chop" being a thing.
Not sure what you mean. The histogram represents the range of the ES contract over specific units of time. Take from it what you like.
"Chop" refers to price not being trendy over a period of time. It doesn't necessarily have much to do with the actual range of the bars. Your chart shows that the average range of a 30 minute bar around lunch time is less than 3 points, and the average range of a 30 minute bar in the morning is over 4 points. That doesn't mean price isn't chopping, though.
Your original post seemed to be talking about volatility at different times of the trading day. The chart I linked to showed the typical volatility pattern during the trading day for most markets. What I have found, and what I think you will find if you look into it, is that during low range periods price is more apt to display the "chop" pattern you reference if the resolution is reduced to a lower time frame. The notion that many traders have, which is that most intra-day range expansion opportunities occur most frequently during the morning or afternoon sessions, is indeed true. That is why the chart I presented is relevant.