Clouds

1.a cumulonimbus clouds( thundercloud, a thunderhead)
A cumulonimbus cloud is the most dangerous clouds in clouds. The height of clouds may amount to 10 km or more. Under this cloud, thunder and a tornado occur or it rains heavily. 

A cumulonimbus cloud may be the tallest in clouds, occasionally may use up the troposhere, and may also arrive at the stratosphere. It is the name made combining "nimbus" which means Latin "cumuls" which means "being piled up" and "rain cloud." A cumulonimbus cloud is that cold air enters high up in the sky, and also the ground can warm by solar radiation etc, and when the difference in temperature the sky and near the ground is large , it occurs.  In clouds, the intense convection has taken place and there are many ascending currents. If a cumulonimbus cloud passes, the rain of a large drop will fall and it will rain heavily for a short time. Hail may come down, or thunder may occur and a strong wind may blow. If it is winter, it will snow strongly. A tornado is also depended on a cumulonimbus cloud.If it is the thunderstorm in summer, it will stop in 30 minutes mostly.

2.the eye of a typhoon
Has you heard that a typhoon has eyes?The eye of a typhoon is a wonderful place. Although a wind strong near a center blows and it is raining heavily in the eye of a typhoon, neither rain nor a wind is almost.
A blue sky may be seen. According to the dictionary, it has weakly wind and no wind in the eye of a typhoon which placed in the center of a typhoon.The center of a typhoon is a downdraft. Although both the center of a typhoon and a high pressure are the downdrafts, those isobars are the opposite. Atmospheric pressure falls in the eye of a typhoon. 

3.nimbostratus
Nimbostratus is from about 600 m to 5,000m or 6,000m, and is classified into the same middle cloud as altocumulus or an altostratus. It is a cloud layer of almost uniform gun metal gray.  The cloud droplet which is making this cloud are snows, the crystal of ice, and raindrops. Nimbostratus occurs near a center of a low pressure and near a front. If a warm front approaches, an altostratus will become thick and will change to nimbostratus. Rain and snow fall not only from nimbostratus but from a cumulonimbus cloud. However, the range in which rain and snow of nimbostratus fall is a range wider than a cumulonimbus cloud. Unlike a cumulonimbus cloud, the method of the rain showers on rain and snow with little change of strength. If covered with this cloud, about 1/3 of Tokyo Tower or a skyscraper will disappear.

4.cirrus

It means thin clouds like the extended floss silk. Although the sun sets, it is dyed red and an orange at the time of twilight, and it is beautiful. "Cirrus" has a meaning called frizzled hair and volume hair in Latin.
Cirrus occurs at the highest place in clouds. For this reason, at sunset, it colors the latest than other clouds , at sunrise, it does earliest.  Even if cirrus has spread in the sky, it is as thin clouds as sunlight is not interrupted.  We are dazzling even if we sees the sun through cirrus, and a shadow is made even if cirrus covers the sun. The place where cirrus has generated is the troposhere upper part to which various weather phenomena have happened. There is little water vapor quantity and temperature is a place not more than -40 ℃. For this reason, since the cloud droplet which is making cirrus is ice, it serves as thin clouds. There are various forms in cirrus.Although cirrus appears also at the time of the fine weather covered with the high pressure, when a low pressure and a typhoon approach, it appears first, and then, the quantity of cirrus increases gradually.