This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.

Passage: Western France, Spain, and other areas skew time zones and shift clocks, in effect observing DST in winter with an extra hour in summer. Nome, Alaska, is at 165°24′ W longitude, which is just west of center of the idealized Samoa Time Zone (165° W), but Nome observes Alaska Time (135° W) with DST, so it is slightly more than two hours ahead of the sun in winter and three in summer. Double daylight saving time has been used on occasion; for example, it was used in some European countries during and shortly after World War II when it was referred to as "Double Summer Time". See British Double Summer Time and Central European Midsummer Time for details. Question: Places like Spain and parts of France effectively go by DST in the winter but add what in the summer?
an extra hour