Pumice is a volcanic rock which is made from lava. It is a very light rock material filled with gas bubbles. It is produced when lava with a high gas and water content erupts from a volcano and then cools abruptly. During the process, the dissolved water vapours in the lava are suddenly released, resulting…
Rain is a form of precipitation of water droplets that are greater than 0.5 mm in diameter. The amount of precipitation that falls all over the world may range from less than 0.1 inches per year in some deserts to more than 900 inches per year in the tropics. It is estimated that every minute…
The structure of a snowflake is quite complex. It is formed from a frozen drop of cloud, which forms the nucleus. The nucleus quickly attracts water molecules around it that freeze instantly. In the process, the attracted water molecules branch out giving the snowflake a unique hexagonal shape. Since the branching out process is different…
Water evaporates from oceans, seas, rivers, etc., and rises up in the atmosphere. At the height of several thousand kilometres, these vapours condense to form clouds and eventually droplets. By this time, the droplet may have travelled many miles from its place of origin. Once the droplets reach a certain size, typically 6 mm in diameter,…
About two billion years ago a meteorite which was about ten kilometres in diameter hit an area near the town of Vredefort Dome near Johannesburg in South Africa. The impact of that meteorite created a crater that is 380 km across. Among the earth’s 130 meteorite crater sites Vredefort Dome is the top third and is…
