Captains read the grass when they should be reading the sky

The toss ritual of prodding the surface and squinting at a green tinge is theatre; overhead conditions decide the first session.

Two captains walk out. One crouches, presses a thumb into the pitch, tugs at a blade of grass. The other nods. Somebody says the word tacky. Then they toss, and the winner says he will have a bowl because there is a bit in it.

Half the time the bit that is in it is not in the pitch at all.

Seam movement off the surface needs moisture in the top layer, and that moisture burns off fast under sun. By the twelfth over on a warm morning it is largely gone and the ball is skidding on. Swing, though, the movement that happens in the air before the ball ever lands, does not care about grass. It cares about the condition of the ball, the seam position of the man delivering it, and to some degree the air overhead. Heavy, still, overcast conditions are worth more to a bowling side than any amount of green on the square. Cloud cover lasts hours. Surface moisture lasts about forty minutes.

So the honest question at the toss is not how much grass is on it. It is what the sky is doing at eleven, and what it will be doing at two.

The grass matters enormously for something else, and this is where the thinking gets muddled. A well-grassed surface binds the top and stops it breaking up on days four and five. Leave grass on and you are not really buying first-morning seam movement. You are buying a pitch that still plays properly in the fourth innings. Which is a completely different bet, and frequently a bet against yourself if you bowl first and then have to bat last on a surface you helped preserve for the opposition's spinner.

There is a bowling consequence too. On a pitch with genuine moisture, a hard length, back of a good length, hitting the deck, gets more out of the surface than a full ball does. Full and swinging belongs to the overhead conditions. Hard and seaming belongs to the surface. Watching a seamer bowl the wrong one is one of the more maddening sights in the sport, because he will get away with it for four overs and then go for three boundaries in the fifth, still banging it in halfway down long after the moisture has gone.

Read the sky. Then decide. The grass is mostly for the cameras, and for day four.