A standard hour (SH) that we normally use is 60 minutes long. A halachic hour (HH) is 1/12 of the time between the start of the day and the end. On a day where there is an equal length of day and night each halachic hour would be 60 minutes, but it is a different length all other days. (Berachos 26b)
Question: Assuming you are in Anchorage Alaska in May and the If a day begins at 5:24am and ends at 10:24 pm how long is each HH between 5:24am and 10:24pm?
Answer: 5:24am to 10:24pm= 18(SH) hours
18(SH) hours x 60 minutes = 1,080 minutes
1080 / 12 = 90 minutes per HH.