An arcus cloud is a low, horizontal cloud formation. Roll clouds and shelf clouds are the two types of arcus clouds. A shelf cloud is usually associated with the leading edge ofthunderstorm outflow; roll clouds are usually formed by outflows of cold air from sea breezes or cold fronts in the absence of thunderstorms.
A shelf cloud is a low, horizontal, wedge-shaped arcus cloud. A shelf cloud is attached to the base of the parent cloud, which is usually a thunderstorm, but could form on any type of convective clouds. Rising cloud motion often can be seen in the leading (outer) part of the shelf cloud, while the underside often appears turbulent and wind-torn. Cool, sinking air from a storm cloud's downdraft spreads out across the land surface, with the leading edge called a gust front. This outflow cuts under warm air being drawn into the storm's updraft. As the lower cooler air lifts the warm moist air, its water condenses, creating a cloud which often rolls with the different winds above and below (wind shear).
People seeing a shelf cloud may believe they have seen a wall cloud. This is a likely mistake, since an approaching shelf cloud appears to form a wall made of cloud. A shelf cloud usually appears on the leading edge of a storm, and a wall cloud will usually be at the rear of the storm.
A sharp, strong gust front will cause the lowest part of the leading edge of a shelf cloud to be ragged and lined with rising fractus clouds. In a severe case there will be vortices along the edge, with twisting masses of scud that may reach to the ground or be accompanied by rising dust. A very low shelf cloud accompanied by these signs is the best indicator that a potentially violent windsquall is approaching. An extreme example of this phenomenon looks almost like a tornado and is known as a gustnado.
A roll cloud is a low, horizontal, tube-shaped, and relatively rare type of arcus cloud. They differ from shelf clouds by being completely detached from other cloud features. Roll clouds usually appear to be "rolling" about a horizontal axis. They are a solitary wave called a soliton, which is a wave that has a single crest and moves without changing speed or shape. One of the most famous frequent occurrences is the Morning Glory cloud in Queensland, Australia. One of the main causes of the Morning Glory cloud is the mesoscale circulation associated with sea breezes that develop over the Cape York peninsula and the Gulf of Carpentaria. However, similar features can be created by downdrafts from thunderstorms and are not exclusively associated with coastal regions.
Coastal roll clouds have been seen over California, the English Channel, Shetland Islands,Lithuania, Eastern Russia, other maritime regions of Australia, off the Mexican coast in the Sea of Cortez, Uruguay, in the Canadian provinces of Nova Scotia and Ontario, and Campos dos Goytacazes and Coronel Vivida bay in Brazil.
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Menstruasi itu berasal dari sebuah kata dalam bahasa Latin, yaitu Mensis , yang berarti 'bulan'. Disebut menstruasi karena secara rata-rata menstruasi datang sekali sebulan. Dan “menstruasi” bulanan ini adalah siklus peristiwa di dalam tubuh yang dikendalikan oleh hormon-hormon.
Cairan yang keluar saat menstruasi terdiri atas jaringan atau sel-sel yang berasal dari penebalan dinding rahim (yang disebut endometrium), darah dan mukus. Dan cairan yang keluar itu kira-kira 200-250 ml perhari, atau sebanyak setengah gelas. Dari jumlah itu, kira-kira 35-60 ml atau tiga sendok makan, berupa darah.
Seorang perempuan pertama kali mengalami menstruasi mulai pada usia 9 sampai 12 tahun. Tapi pada umumnya, rata-rata perempuan menstruasi pertamanya terjadi pada usia 11 tahun.
1. Perut kembung
2. Sakit pada sendi dan otot
3. Sakit kepala dan cepat lelah
4. Berat badan bertambah karena retensi cairan
5. Payudara terasa kencang dan kadang disertai rasa gatal
6. Sering mengalami kecemasan
7. Mudah marah, suka menangis tiba-tiba, dan mudah tersinggung
8. Insomnia (sulit tidur)
9. Mengalami perubahan pada selera makan
hahahahahhaha ! SAKIT OKAY
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