Seasonal weather at the VLA

Including practical astronomy and other interesting aerial phenomenon

Purpose: This page is intended to present weather related topics of interest and usefulness to VLA operators, as well as interesting and unusual sights related to other atmospheric and space sciences which our clear, dark skies make possible.

Overall/General (designations of location, altitude, climate type etc here)

Spring
Summer
Fall
Winter

Spring
- General: Vernal equinox (literally, 'equal night'), occurs when the Sun crosses the celestial equator from south to north, resulting in 12 hours of day and night each, worldwide. This point on the ecliptic is also known as the 'first point of Aries', and redefines the origin of celestial longitude (Right Ascension, or RA).

Due to precession, the Earth's axis of rotation advances along the sky at the rate of about 1 degree per 72 years. This results in the 'displacement' of any point's coordinates of just under one arcminute per year. Since astronomical 'epochs' are re-computed in 50-year intervals, the difference in Right Ascension for an object near the celestial equator (the effect lessens for higher declination sources, and even reverses in regions near the celestial poles) will be seen to equal an increase of about 3 minutes of *time* between epochs.

Examples (to be taken from and/or linked to VLA calibrator manual)

- Weather and astronomy topics

Winds! - This area is known for its high spring winds, particularly during the months of April and May... (discussion of ACU/anemometer cutouts/procedures)

- Things to look for:

High-altitude research balloons - In the spring (and again in the fall), the NSBF at Ft. Sumner NM conducts flights of high-altitude research balloons. When a launch is scheduled, we will be notified because some of their telemetry lies within L-band. Once a balloon is launched, the above website will provide a realtime gps ground track, useful for determining a source of interference or simply to locate the 'object'

(Other seasons similar, narrative, links, diagrams etc pending)
Summer
- General
- Weather
- Things to look for:

Fall
- General
- Weather
- Things to look for:

Winter
- General
- Weather
- Things to look for: