BILLINGS – Tomorrow marks the end of a rainy spring here in Billings. The summer solstice ushers in the summer season, at least as far as the calendar is concerned.
In Montanan we know that Mother Nature might have other ideas.
The sun will appear directly overhead of the Tropic of Cancer, at 23.5 degrees north latitude. (It is no coincidence that the earth is tilted on its axis at 23.5 degrees, and this tilt is the reason for our seasons.)
The summer solstice marks the longest day of the year, the day when places in the northern hemisphere receive the greatest amount of sunlight.
The reason that the warmest day of the year often does not coincide with the longest day of the year with the longest sun exposure is due to what is called a radiation lag.
This refers to the fact that for several more weeks the amount of radiation coming into the atmosphere is greater than the amount leaving it, allowing for further warming.
This is very similar to what occurs on a daily scale. Even though the sun is directly overhead at noon (slightly later at northerly latitudes) the heat of the day does not occur until later in the afternoon, when there is still a greater amount of radiation coming in than going out and thus warming still occurs.
For Billings, it was a spring we might rather leave in the rearview mirror. It started with a winter that would not relinquish its hold on the Magic City and has continued with tumultuous weather, including severe storms and heavy rainfall and serious flooding concerns.
The rainiest day of the season was May 23 with a total of 1.54 inches. There were four days where daily rainfall totals exceeded one inch.
The warmest day was a 90 degree tie on June 4 and 9. The coldest day was back on April 6 where temperatures only managed to climb to 18 degrees.
The Center for Climate Prediction released their seasonal summer forecast at the end of May and their prediction indicates a good chance that things here in Montana are warmer than normal over July, August and September.