The accompanying figure is the logical extension to last week’s illustration of water flowing in, and then out of a tank. Depending on the flow rates, the water level will reach an equilibrium because the higher the water is in the tank the more pressure at the bottom and the greater the flow rate out of the tank.
Thus so it is for the radiant energy from the sun (in the visible part of the spectrum) at the top of the tank and the outbound radiant energy leaving at the bottom in the IR (infrared) part of the spectrum. Just as the height of the water reflects the equilibrium water level, the temperature reflects the relative balance of radiant energy coming into and out of the atmosphere.
The illustration here shows why the daily and seasonal temperatures vary, and explains why the highest temperature during the day is in late afternoon when the sun is most directly overhead at noon, and also why the hurricane maximum and the highest temperature during the year is in mid September (close to the autumnal Equinox, the beginning of the Autumn season) instead of June 22 (the summer solstice when the sun is most directly overhead during the whole year).
The sun shines on each spot on the earth only about 12 hours a day (more or less depending on the latitude). The rest of the time, the earth’s rotation is presenting a different face to the sun and it is dark. But the earth radiates energy out to space 24 hours a day, sunlight or not. This is because everything radiates energy just because it has a temperature above absolute zero. The amount of energy radiated and the wavelengths where it is radiated depend on the temperature. This is analogous to what comes out the bottom spigot.
So as the earth radiates in the darkness, the earth cools. This is true every night and also in the fall and winter months. Then when the sun shines more, the earth begins to warm and the temperature rises starting at sunrise, and also during the spring and summer. At 12 noon/or and on June 22 the sun is highest in the sky and the heating is at a maximum, and more than the earth can radiate away -- so the temperature rises. It will continue to rise as long as the amount of energy coming in from the sun exceeds that being radiated away. It isn’t until late in the day or in the Fall that the energy coming in is as low as the energy being radiated away. At that point the earth stops heating and begins to cool. It is that point during the day that it is the hottest, and it is at that point during the year where it is also the hottest. As long as the heat coming in is greater than the energy going out, the temperature will continue to rise.
Hurricanes thrive on warm ocean temperatures and warm air. This is at its peak in mid September – hence the peak of the hurricane season. This year, these conditions are conducive for tropical storm development in the Pacific than in the Atlantic. The storms what we haven’t had in the Atlantic have occurred in the Pacific basin. The Atlantic has suffered from mild El Nino conditions and dry air intrusion into potential storms. Much of the same adverse conditions as characterized the last several years. A harbinger of things to come?