You can tell how stable the atmosphere is by the shape of the clouds.In very simple terms the stability of the atmosphere is its tendency to settle or not when disturbed vertically. Things can cause these upwards disturbances such as the air moving up the side of a mountain as it crosses the land or it being heated by warm ground below making it expand buoyantly. If the atmosphere is stable it will tend not to displace much vertically but if unstable large billowing plumes of air can rise.When the atmosphere is unstable like that you see these plumes as the fluffy rising cumulus clouds that puff up surrounded by clear sky.But when the atmosphere is stable the clouds you see will tend to be flat layers of cloud - stratus clouds.When it’s in between sometimes you can see flat layers of clouds with puffy plumes rising up or layers with lots of little gaps in them.Often you can see different types at different heights - low ones puffing up and middle ones as flat layers of puffs with gaps around each one.You can tell a lot about the stability of the atmosphere by looking at the clouds.
I mostly agree with Honza Chylik, but want to clarify something: it's relatively uncommon for density to increase with height in the atmosphere, except in a shallow layer a few meters deep near the surface. Such a condition arises when the temperature decreases with height at a rate greater than 34 deg C per kilometer (called the "autoconvective lapse rate). It creates the shimmering effect we often see on warm, sunny days. A more widespread definition of static instability is when the lapse rate equals or exceeds the dry adiabatic lapse rate of 9.8 deg C per kilometer. In such situations, cloud-scale thermals are unstable due to buoyancy.There are many different types of atmospheric instability on many different scales associated with many different physical processes, so the question is ill-posed.
The rate at which the air surrounding air cools as height above ground increases is called the ambient lapse rate or the environmental lapse rate (ELR) or the prevailing lapse rate. If air is heated by the ground (say the ground is hotter than the surrounding ground) then it rises, being hotter and therefore less dense than the surrounding air. This parcel of air continues to rise as long as its temperature is greater than the surrounding air. If the surrounding air becomes hotter than the parcel as we rise (an inversion prevails) then the parcel will sink. When parcels continue to rise the atmosphere is said to be unstable. If you can somehow make air hotter as altitude increases you can make the atmosphere stable. This could be done by putting a lot of water vapour at altitude in the air and heating it with infrared radiation. It could also be done by heating clouds with infrared radiation and microwaves - air would become hotter where heating takes place (after evaporation). The above is modified when there is a lot of water vapour in a parcel of air, because water vapour in air makes the air less dense.
When is the best time to use a telescope?
The best time is when you have the best view of the object you want to see. That does not always mean at night. For example, the Moon. It is often visible in a clear blue daylight sky, and is interesting to look at surrounded by a blue background instead of black. A full moon straight overhead at night is a hard thing to look at for a long time without a filter because it is so bright. Looking at it when it is in a "smaller" phase is perhaps easier, and you see more crater detail. This may mean looking at it in the early evening around dusk. For another example, Jupiter and Venus. Right now, they are visible from maybe 4 AM until 7 AM, then the daylight renders them almost invisible, but some of the best pictures of Venus and Jupiter are taken during low-level daylight when the contrast between the background and the planet is not so harsh. Other objects are best viewed when they are at their highest point in the night sky, because at that point you are looking through the least amount of atmosphere. That time could be any time during the night. Saturn, for example, is at its highest point around midnight. Mars is now at its highest point at closer to 8 PM. Still other times, objects are visible at sunset. A thin crescent moon, for example, with the dark side faintly lit by Earthshine, is a beautiful sight that can only be seen in the late afternoon and early evening. Don't let these jackholes on Yahoo! Answers give you a bunch of smartazz answers. I would suggest you get a copy of an astronomy magazine or the Farmer's Almanac and check it for rise and set times of the objects you want to view, then go look at them and see what your preference is. The reality is that astronomical objects are visible 24/7 except if it's cloudy. Just don't look at the sun with your eyes. There are filters and projection screens that attach to your telescope for that.
I wonder what it is that leads you to ask this question—that might provide some insight.Are you lacking in passion altogether—*nothing* gets you irritated, annoyed or angry? If so, that’s very different than being aware of feeling angry but not acting on it. If you’re very good at managing your emotions, that’s great for you. But if injustices don’t upset you, if being ignored or disrespected doesn’t give your emotions any bump at all…then I would say something else is going on.Some of us (including me) were raised to feel that anger is simply unacceptable. I managed to stuff down all those angry, upset feelings and act as though nothing bothered me, pretty much through my teens, 20s and even into my 30s I think. But eventually it caught up with me in the form of depression. In some areas of life I was a real mess, pretty much non-functional. It gives me heartache now to think what I did to those around me because I was so disconnected from them and from myself. And I had some WTF moments when I’d blow up with no warning. I’m slowly working through all this stuff.It’s better to have *all* your feelings, believe me.
Times change.In Victorian England, you were supposed to keep a stiff upper lip. The best people were the people who did not express emotion and kept calm.Then with the advent on cheap soaps on television, people were suddenly advised to let it all hang out. It is amusing to me that in the US, the police will consider you a suspect if you don’t fall in tears and hysterics when a person dies next door.Maybe you are collected and well organized. Congratulations.Don’t change.My hero of cool is Neil Armstrong. I think that if the computer was telling me that I am getting short of fuel when landing on the moon, I would crash. Armstrong did not.When he retired, he once cut one of his fingers. He put it on ice and drove to the nearest hospital to have it fixed.Cool as I want to be, I would still be looking for the car keys. So, please, be like Armstrong. That is the only way to go to the moon.