A pyroclastic flow (also known scientifically as a pyroclastic density current) is a fast-moving current of hot gas and rock (collectively known as tephra), which reaches speeds moving away from a volcano of up to 700 km/h (450 mph).The gas can reach temperatures of about 1,000 Â°C (1,830 Â°F).Pyroclastic flows normally hug the ground and travel downhill, or spread laterally under gravity. Their speed depends upon the density of the current, the volcanic output rate, and the gradient of the slope.They are a common and devastating result of certain explosive volcanic eruptions.yroclastic flows normally hug the ground and travel downhill, or spread laterally under gravity. Their speed depends upon the density of the current, the volcanic output rate, and the gradient of the slope.
Optimal Reading. An optimal reading is considered anything lower than 120/80. The actual number of 120/80 is not considered perfect--but actually numbers lower are considered to be optimal. For example, someone with a blood pressure reading of 116/76 has an optimal reading.ptimal Reading. An optimal reading is considered anything lower than 120/80. The actual number of 120/80 is not considered perfect--but actually numbers lower are considered to be optimal. For example, someone with a blood pressure reading of 116/76 has an optimal reading.
If your blood pressure is optimal, this is great news. By following our healthy living advice, you will be able to keep it this way. If your blood pressure is above 120/80mmHg, you will need to lower it. Most adults in the UK have blood pressure readings in the range from 120 over 80 (120/80) to 140 over 90 (140/90).If your blood pressure is within this range, you should be taking steps to bring it down or to stop it rising any further. Our five top tips will show you how.f your blood pressure is optimal, this is great news. By following our healthy living advice, you will be able to keep it this way. If your blood pressure is above 120/80mmHg, you will need to lower it. Most adults in the UK have blood pressure readings in the range from 120 over 80 (120/80) to 140 over 90 (140/90).