Geomagnetics, Ionosphere, and Solar Convection
The morning smells fresh because:
The earth's magnetic sphere creates ions which destroy or break up pollution particles and microbes. They also push unpleasant things by their charge away from the earth into the midatmosphere, where they are chilled out at low temperatures. This happens even at night.
The sun's rays heat the earth and that heat convects upwards towards the atmospheric ceiling from the equator. It also moves up and down at 30* and 60* latitude[longitude?] and then at the north and south poles streams downwards to the ground as all points meet and have no more room to expand to. The earth is thus encircled by atmospheric belts. This causes very windy conditions, high pressure zones, and circulation from the upper[chilly] atmosphere at both poles. Sunlight also reflects off the white snow caps rather than become absorbed and turn into heat. Flying along 30* or 60*, or flying upwards at the equator can cause turbulence and affects weather.
We rely on the ionosphere to freshen the planet. This is critical among earth's geomagnetic properties. Mars has no such belts, a very thin atmosphere, no speakable convection, and a very weak magnetic field. Their planet's surface is not continuously freshened, has no oceans to regulate temperature, and is not suitable to support life.
I believe this principle is demonstrated at a certain site describing the most likely and unlikely routes to human extinction.
I speculate that oceans function as emotional buffers, since water forms crystals based on mood. The energy of the mood could be evened or consumed by the bodies of water. This may also happen in high humidity, and be less present at higher altitudes.