Observatorio fabra

Tomás Méndez Díaz
2070346

FIELD TRIP REPORT

CONTENTS:
1. Anemometer
2. Anemograph
3. Weather vane
4. Heliograph
5. Barometer
6. Barograph
7. Subsurface thermometers
8. Rain gauge
9. Evaporimeter
10. Nephoscope



INTRODUCTION
The field trip to the Fabra Observatory was made with the idea to introduce some of the meteorological devices that areused to make the measurements. Since the observatory only does guided visits on Sundays, the date was 15th January 2012, at 11:00 am.
The visit was guided by one of the professional meteorologist that works there. Starting with a introduction of the history of the place, the trip through the observatory was really impressive and interesting. We pass through the 3 levels of the building. Level onewas more focused on the old devices, today out of service. Including, the first meridian telescope in one of the rooms and the principal devices used in meteorology, seismology and astronomy. The second level leaded us to a third one, which contains the current telescope that is used for the measurements nowadays, and some public activities such as sky observation for groups of visitors. The onlyinteractive activities we found at the place were related to their website on a computer screen, and the seismograph monitor to show the movement waves.






EQUIPMENT AT THE STATION
1. ANEMOMETER
The anemometer is a device to measure the wind speed. The one used at the Fabra Observatory is the windmill type or propeller anemometer. Its axis of rotation must be parallel to thedirection of the wind and horizontal. The axis changes with the direction of the winds. It also combines a propeller and a tail on the same axis to obtain accurate and precise wind speed and direction.
[pic] [pic]
Windmill Anemometer Fabra Observatory Anemometers

2. ANEMOGRAPH
The anemograph is the device that registers the wind direction andits speed in meters per second. It is a compact device plugged in the electric current with two exit channels: one for the speed and the other for the direction of the wind. It makes a graphic record of the two parameters continuously and simultaneously.

[pic]
Anemograph
3. WEATHER VANE
The weather vane is an instrument to show the direction ofthe wind. Its weight is evenly distributed on each side of the surface and the pointer moves freely on its axis. The side with the larger surface area is blown away from the wind direction, so the smaller side, with the pointer, is pivoted to face the wind direction.


[pic]
Weather vane


4. HELIOGRAPH
The heliograph is adevice to measure the amount, in time, of sunlight in a day. The sunrays reflect through a glass ball burning a cardboard with the hours of a full day on it. There are not burning parts during a cloudy and dark day.
[pic] [pic]
Fabra Observatory’s Heliograph Heliograph cardboards



5. BAROMETER
The barometer is an instrument to measureatmospheric pressure. It consists of a glass tube filled with mercury, and its open end is submerged in the basin beneath the graduated cylinder. To make the vacuum, the capillarity tube is provided with a device that prevents the passage of any air bubbles. To measure the temperature of the mercury, there is a thermometer holding to it. The barometer is constructed so that the relation betweenthe sections of the inner tube and basin are known. The scale is such that the mercury rises in the tube are compensated by the declines in the level of mercury in the basin.

[pic] [pic]
Barometer system Barometer

6. BAROGRAPH
A barograph is a recording aneroid barometer. It produces a paper or foil chart called barogram that records the...