Process of circulation of air :
(i)When air is heated it expands, becomes light and rises up.
(ii) Cold air is dense so, it sinks down.
(iii) When hot air rises up, cold air from surrounding areas fill in the gap.

Distinction between Rainfall and Snowfall

In areas of lower temperature, the air is cold. It is, therefore, heavy. Heavy air sinks and creates a high pressure area. High pressure is associated with clear and sunny skies.

Green plants use Carbon dioxide to make their food and release Oxygen. Humans or animals release Carbon dioxide. The amount of Carbon dioxide released by humans or animals seems to be equal to the amount used by the plants which make a perfect balance. But this balance is disturbed by burning of fuels, which add billions of tons of Carbon dioxide in the atmosphere. As a result, the increased volume of Carbon dioxide is affecting the earth's weather and climate.

Differences between weather and temperature are

When the moisture from engines of jet planes condenses, we see trail of this condensed moisture for sometime. As soon as air movement disturbs the moisture, trail disappears.

The carbon dioxide balance gets disturbed by burning of fuels such as coal and oil. They add billions of tons of carbon dioxide into the atmosphere each year. As a result the Earth's weather and climate get affected.

Astronauts have to wear special protective space suits filled with air when they go to the Moon. If they did not wear these space suits, the counter-pressure exerted by the body of the astronauts would make the blood vessels burst. The astronauts would bleed.

Temperature in cities is much higher than that of villages. The concrete and metals in buildings and
the asphalt of roads get heated up during the day. This heat is released during the night. Also, the crowded high rise buildings of the cities trap the warm air and thus raise the temperature of the cities.

Nitrogen is very important for plant's survival. They cannot take nitrogen directly from the air. Bacteria that live in the soil and roots of some plants take nitrogen from the air and change its form, so that plants can use it

Atmosphere consists of mainly nitrogen (78%), oxygen (21 %), argon (0.93%), carbon dioxide (0.03%) and other gases like helium, ozone and hydrogen (0.04%).

The pressure exerted by the weight of air on the Earth's surface is called air pressure.

The convectional rainfall, the orographic rainfall and the cyclonic rainfall are three types of rainfall.

Weather is the mixture of events that happens each day in our atmosphere including temperature, rainfall and humidity. Weather is not same everywhere.

Nitrogen and Oxygen are the two gases which make the bulk of the atmosphere.