What jitter value should I use for this scatter plot? I plotted a scatterplot between humidity and temperature (air) in centigrade. I got the following graph;

It is evident that the points fall in discrete columns. This might be because of the rounding of the humidity estimates to one decimal point. To break up these columns, I think some random noise (jitter) could be added to the humidity estimates. I want to know what value of jitter should I use? The new variable (jittered humidity) shall be of the form; humidity + jitter.

There is not a unique way to do this, nor is it easy to formalize the space of possibilities here, so here is one way to set the jitter.
In your case, there appears to be even spacing between columns of points. For a point from a column of points at $x=a$ you could uniformly sample a new position of that point from $[a - \frac{w}{2}, a + \frac{w}{2}]$ where $w$ is the width between columns of points. This should almost-surely protect the order of points along the horizontal axis between columns while spreading out the values.
