Fifty percent of the total mass of the atmosphere is located in the lower 5.6 km (18,000 ft) of the troposphere. It is primarily composed of nitrogen (78%) and oxygen (21%) with only small concentrations of other trace gases.
Having irregular periods is very common. I see them in my practice all the time. The causes can range from something insignificant to something that requires treatment. For example, if you're a teen, your body's hormones can fluctuate and take some time until they find a balance.
You may see some dark clumps or clots of blood, which is normal. Your period may be heavy the first day or so each time and then decrease on later days. Periods usually last between three and five days. It is normal to have periods that are shorter or longer, up to seven days.It is also normal if your periods are not the same number of days each month, especially in the first years.atural body chemicals, or hormones, cause your ovaries to release one egg about once a month. Most months, the egg and the lining of your uterus come out of your vagina as your period. This is part of your menstrual cycle. This cycle is what makes it possible for a woman to have a baby.