Is air on the same level is a question with too little information. Air is all around, surrounding everything. The air could be considered on the same level of the people and the land due to it's existence. If the question is referring to air being compared to another substance, compound, or item.
the air mass and over lands are the same cause they are both in the same level
The composition of air is practically the same at the level of earth.
They are about the same.
The free convection level is the height within the atmosphere where a parcel of air can rise freely solely due to its buoyancy compared to the surrounding air. At this level, the parcel's temperature is the same as the surrounding air, and it does not require external lifting mechanisms to ascend.
Air temperature and sea level pressure are directly proportional to each other at the same location on Earth. This means that as air temperature increases, sea level pressure tends to decrease, and vice versa.
The air pressure at the top of our heads is the same as the air pressure at any other point at the same elevation above sea level. The air pressure decreases with increasing altitude due to the weight of the air above pushing down on the air below, creating the atmospheric pressure we experience.
At high altitudes, the oxygen level in the air decreases because the air is less dense due to lower atmospheric pressure. This reduced oxygen level can lead to symptoms of altitude sickness like fatigue, dizziness, and shortness of breath in individuals not acclimated to the altitude.
The Boiling Point of a Liquid (a Fluid) is dependent on its Surface Pressure (air pressure). The Air Pressure (due to increased altitude) is LOWER in Henderson than at Sea Level.
It depends on the altitude. Taken normally at sea level, warm air has lower pressure than colder air at the same altitude.
Assuming you are talking about air pressure, atmospheric pressure is created by the weight of the air resting against the earth. the higher up you go, the less air stacked on top of itself, and the pressure is less, until there is no more air at all (space). The pressure of air at sea level is relatively the same around the world because of all the water flows to the same level. this obviously changes with storms and hurricanes - as those move some of the air out of the way. So if you were to go below sea level, there would be more air on top of you, and the pressure would be higher. In death valley (well below sea level) the atmospheric pressure is much higher than at sea level. To answer the question, No, pressure is not negative below sea level. It is greater than at sea level.
It may be the same temperature at ground level but the temperature (and behaviour) of the air column above you will be different.
grassy and windy and exactly the same as before 1850 but not 1850