Depending on how the peaks and valleys of the Milankovitch cycles line up, or don't, they can change how much solar radiation hits Earth's mid-latitudes by up to 25%.
But their costs of deposits, which is the main form through which banks fund themselves, has stayed largely unchanged or are not nearly changed to the same degree as the price of loans.
经济学百科 The Economics Book (Big Ideas Simply Explained)
It took only a small step from this to see how the demand for different products, such as bread and caviar, varied by differing amounts when the price of those products changed.
Solar days use the sun as a reference point for when " noon" is, but the length of time between when the sun is highest isn't constant - it changes up or down by a minute over the course of the year.