The sun is the world’s biggest and brightest source of heat, so why does it get more intense in the Northern Hemisphere than the Southern?
And is there any truth to the notion that the Northern hemisphere is the better place for cooling?
BBC News has been analysing the sunspot numbers for the past 20 years and discovered that the Sunspot Index (SII) in the North has increased over the past decade, while the SII in the Southern has decreased.
The reason for the difference in the SISI is partly down to the fact that we now have a greater capacity to absorb the sun’s rays.
So, as a result, the SIs have become more sensitive to changes in the Sun’s brightness.
But it’s also down to how the sun is behaving in the Solar System, says Michaela Hochberg, the author of a new book about the sun and climate.
“You don’t really get a sense of how the solar system is changing from satellite images, and it is because of the way that the Earth orbits the Sun, that the SISS [Sunspot Index] varies significantly,” she explains.
“So we know it is a little bit hotter in the northern hemisphere than the southern hemisphere, but that’s not the whole story.”
Hochwell’s book is titled The Sun: A Personal History of the World’s Most Powerful and Destructive Sunspot.
In it, she discusses the differences between the Sissois in the different regions of the world and the difference between the temperatures in different parts of the Northern and Southern hemispheres.
Here’s a selection of the key points.
The sun’s brightness varies from place to place.
“There is some variability in the brightness of the sun in the southern and northern hemispies, which is why there are different sunspots in different regions,” she says.
“The Sunspot index changes by an average of two points every 10 years, which means that there are more and more sunspot variations in the north and south of the globe than in the centre.”
“What you do not see in satellite images is that this gradient varies substantially from place and time.” “
There are also variations in how much solar energy is reaching the Earth. “
What you do not see in satellite images is that this gradient varies substantially from place and time.”
There are also variations in how much solar energy is reaching the Earth.
“When we see a certain type of sunspot in the sky, that’s because the Sun is still burning, so it is not burning up as much energy as it would be in a different place,” she adds.
“However, when the sun goes into a state of low activity, like the winter solstice, it is actually burning more energy than it was in the summer solstice when it is active.”
The average temperature in each region is affected by the location of the Sun.
“It’s not just that the northern half of the planet gets hotter than the south, because that’s also true in the South and the Sun goes through a period of low sunspot activity,” she notes.
“This is because the northern region gets cooler than the South because of its own magnetic field and because the north gets warmer because it has more sunlight.”
“And when you take that temperature gradient and adjust it for different locations and different seasons, it’s not really that far off the average temperature.
So there’s no reason why you shouldn’t expect a temperature gradient in the middle of the hemisphere.”
In the Northern hemispiece, for example, it could be as much as 3 degrees Celsius warmer than in winter in the winter of 1998.
“In summer, we have much cooler summers than winters, and this makes the difference even bigger. “
If you think about it, the average annual temperature for the northern hemisphere is about 3 degrees C warmer than the average summer temperature,” she points out.
“In summer, we have much cooler summers than winters, and this makes the difference even bigger.
So it’s more likely to be warmer than what you would expect if the Sun was doing its thing in the south and not in the central.”
The Sun’s activity in the Earth’s orbit varies throughout the year.
“Each year is different in that it’s always getting brighter and hotter and more energetic, so the SSS is actually much more sensitive in the autumn,” she continues.
“As a result the SIST [Sun’s Surface Temperature] in the Arctic is very low, which causes the SISM [Sun Spectral Isotope Spectroscopy] to be very low in the same area.”
The SIS [Sunspots Isotopic Index] is a measure of how much heat is escaping the sun.
“We know that in winter, the sun gets really dark, so we don’t see a lot of SISS, but in summer, the Sun has got to do all the sunburn