The Vault is Slate’s history blog. Like us on Facebook, follow us on Twitter @slatevault, and find us on Tumblr. Find out more about what this space is all about here. Between the advent of railway ...

Abstract The Hovmöller diagram or the trough–ridge diagram, a simple longitude–time diagram, was designed in 1948 by Ernest Hovmöller (1912–2008) to help understand certain features in the dynamics of ...