If the sun is getting stronger, why was it still cold outside?

ALLISTER AALDERS weather@saltwire.com @allistercanada



SaltWire Network


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While we've seen wild fluctuations in temperature this winter, some of the brightest days near the end of February into March were also some of the coldest, especially in Newfoundland and Labrador. Rick Maddigan asked, “If our heat comes from the sun, why has it been so cold lately when the sun is getting stronger and stronger?” Our sun is the primary source of energy warming the Earth. Still, several factors impact how warm or cold it gets outside. The length of daylight and sun angle is critical. In the wintertime, the sun angle is at its lowest in the Northern Hemisphere, with low amounts of daylight hours if the sun's shining. However, as Rick noted, the sun gets stronger as the angle increases. This is where air masses become a factor. An air mass is a large body of air with generally uniform temperature and humidity. There are various air masses across North America, and as an air mass moves from the source region to another location, it modifies. The modification of airmasses can take several days, and this lag can prevent the sun from warming a cold airmass quickly — hence a bright sunny day in late February can still be frigid. There are other factors at play too. Snow on the ground has a high albedo and reflects solar radiation that would otherwise be absorbed to heat the Earth. Wind speed and direction are also key — a southwest wind is often much warmer than a northwest breeze. The bottom line is that days are getting longer, the sun angle is getting higher and warmer temperatures are on the horizon. Allister Aalders is the weather specialist for the SaltWire Network, providing forecasts and analysis for Atlantic Canada. #AskAllister