Geography Current Affairs

Century’s longest total lunar eclipse of 1 hour 43 minutes to occur on July 27-28

Union Ministry of Earth Sciences has announced that Century’s (2001 AD to 2100 AD)longest total lunar eclipse of 1 hour 43 minutes will occur on July 27-28, 2018. The entire eclipse will be visible from all parts of India. It will also be visible in region covering Asia, Australia, and Russia – except northern part, Europe, Africa, east of South America and Antarctica. The partial eclipse of Moon will begin on July 27, 2018. Later, Moon will be gradually covered by Earth’s shadow and totality phase will begin on July 28 and the total eclipse will last up to 2h 43m. Then the Moon will start to gradually come out of Earth’s shadow and partial eclipse will end on July 28, 2018.

Longest Total Lunar Eclipse

In this particular eclipse, Moon will be passing through central part of Earth’s umbral shadow. During this time, Moon is located at apogee (i.e. at farthest from the Earth) in its orbit and will be moving at slower speed in its orbit. During this transition phase, it will take longer time for Moon and greater distance of Earth’s umbral shadow to travel, making it longest duration of total eclipse of this century. Such long duration of total lunar eclipses earlier had occurred on July 16, 2000 for totality duration of 1 hour 46 minutes and on June 15, 2011 for totality duration of 1 hour 40 minutes.

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Meteorological Department issues warning of another dust storm in UP, Rajasthan

Indian Meteorological Department (IMD) has issued warning of another dust storm and thunderstorm in parts of Uttar Pradesh and Rajasthan. The satellite images have shown wind pressure developing in two states leading to thunderstorms, gusty winds and heavy rain. It also has forecasted thunderstorm accompanied with squall is also likely at isolated places over Uttarakhand, Sikkim, West Bengal and Odisha. The fresh warning comes after two north Indian states were earlier hit severe dust storm, which took lives of over 100 people and left trail of destruction.

Reasons for formation of rainstorms and duststorms

Rainstorms (thunderstroms) and duststorms arise from similar meteorological conditions. They are almost always preceded and caused by spell of intense heat. Thunderstorms occur when atmosphere has moisture and duststorms take place when moisture is not present. Such events take place due to local instability arising out of deviation from normal temperature difference between upper and lower atmosphere. Thus, these events themselves are very localised both in time and space.

In recent rainstorms and duststorms cases in Uttar Pradesh and Rajasthan, moist easterly winds from Bay of Bengal reached up to Himachal Pradesh colluded with dry winds from north-westerly direction. The two systems destabilised equilibrium temperature difference between upper and lower layers of atmosphere, leading to conducive conditions for thunderstorm and duststroms. The final trigger, however, is development of largescale air-circulation system. Many parts of India witness build-up of surface heat during this time of year. The places that were hit by recent storms had seen heat-wave like conditions.

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