Sometimes the breakthrough for a new technology does not materialize in one of those fields which receive most attention and where everybody expects the solution. When the British needed a practical method for determining a ship's longitude in the 18 century, they spent many decades gazing at the stars, compiling lunar tables and searching for astronomic methods for determining longitude. But t...

In the 1700s, scientists, sailors, engineers and explorers were trying to work out how to navigate east to west at sea. The stakes were high; many lives were lost because sailors could not reliably measure longitude. Eventually, the invention of accurate timepieces allowed sailors to use the time in their current location, and the time at a fixed reference, to calculate longitude. But how do lo...

At each point during your walk, the altitude reading will give some indication of your progress, especially when compared to readings from earlier points, but at no time will you receive complete directions to the top of the mountain. You will always be guessing, but in an educated manner based on your previous longitude-latitude locations and their altitudes. For example, if, during the past 2...

We study the spatial and temporal variability of summer marine fog in Chukchi–Beaufort region (175°E?150°W, 70°–86°N) using in-situ visibility measurements aboard Chinese research fleet Xuelong (I II) a product we derive Vertical Feature Mask spaceborne Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observation (CALIPSO) observations. The observations show that frequency has maximum ?18% ear...

Because of their importance in the accurate modeling of the Earth’s orientation in space, some non-negligible predictable effects on precession-nutation are investigated. This paper considers the coupling effects between the axial and the equatorial components of the Earth’s rotation vector in the dynamical equations, and the effects of the second order lunisolar torque due to the Earth’s zonal...

This paper considers a longitude distribution of sunspot groups over 1982–2013, using data from the National Geophysical Data Center (Boulder, USA). The space-time distribution of sunspot groups is analyzed in coordinate sectors calculated from heliographic longitudes of the groups. A longitude extent of a coordinate sector is compared to the average size of one active region (30–40°). Then, in...

Results are presented from a multi-instrument study of the spatial distribution of the summertime, polar ionospheric electron density under conditions of relatively stable IMF Bz<0. The EISCAT Svalbard radar revealed a region of enhanced densities near magnetic noon that, when comparing radar scans from different local times, appeared to be spatially confined in longitude. This was identified a...