Lightning can be detected from thousands of miles away. See http://www.blitzortung.org/Webpages/index.php?lang=en&page_0.... Turn on "detectors" on the right to see the distances involved.

That site works by a using a network of cheap EMP detectors. It uses the timing differences from each sensor to trilaterate the position of the lightning strike.

That's a nifty website!

Antennas, see https://en.wikipedia.org/wiki/Lightning_detection

You can detect lightening using ground based detectors: http://en.wikipedia.org/wiki/Convective_storm_detection#Ligh...

This specific delay though was caused by convective clouds being too close to the launch. This was probably determined with either ground based radar, or visible/IR images from satellites.

Using radio, presumably.

There is a considerable body of research on detecting the presence and range of lightning: http://en.wikipedia.org/wiki/Lightning_detection

Here's a link to a live Live lightning map: http://www.blitzortung.org/Webpages/index.php?lang=en