Casella CEL Campbell Stokes Sunshine recorder User Manual

Side 5 CAMPBELL STOKES SUNSHINE RECORDER

User Instructions

Side 6

CAMPBELL STOKES SUNSHINE RECORDER
User Instructions

October 2000

Holes will be found at one end of the bowl
and a tapered pin attached to a chain to fit
them. This is to enable the card to be pierced

7. EVALUATION

Depending on the curved card in use, the
hourly division varies in width from the top to
bottom. Therefore care must be taken when
measuring the length of a burn.

To help calculate the length of a trace when it
has been interrupted, a template is available,
M114041. Made from transparent plastic, it
has two different grids printed on it, one with
parallel sides at the same spacing as the hour
lines on a straight card. The other grid has
tapered sides with the same spacing as the
hour lines on the curved recording card.

Each grid is sub-divided into 10 equal divisions
as shown in Figure 6.

1. Place the template over the recording card
using the appropriate grid, aligning it with
the hour lines.

2. Count the number of divisions from the
hour line to the end of the burn, one
division equals 6 minutes.

3. Add the length of the burns together to
achieve the duration for one day.

4. Alternatively take a sheet of paper.

5. Lay the edge along the trace and mark its
start and end points.

6. Move the sheet
along to the next
trace.

7. Align the end of the
first burn with the
beginning of the
next and mark its
length.

8. Repeat this until you
have noted the
length of all the
burns.

9. Lay the edge of the
paper along the sun

BURN 1

Figure 7: Total interrupted burns for one day

and positively located in place, as in some
regions birds peck at the cards and move
them.

card the same distance from the edge as
the burn.

10. Starting from a convenient hour line, the
total distance will give the duration of
sunshine for one day. See Figure 7.

When the record has been made by a
midsummer sun, the burn will spread, but in
midwinter or in a haze it may only be just
recognizable.

FOR USE WITH
STRAIGHT CARDS

Figure 6: Grids on template M114041

BURN 2

TOTAL DURATION

FOR USE WITH
CURVED CARDS

In the former case, the end of the
burn is taken to lie halfway
between the centre and the
extreme edge of the curved end of
the burn, but in the latter case, it
should be measured from the
extreme end. See Figure 8.

MIDSUMMER

Figure 8: Where to measure burns

MIDWINTER

8. SERVICING

The instrument is virtually maintenance free,
regular checks of the trace as described
earlier are recommended. Keep the sphere
clean using a non-scratching cloth, and
remove any debris, frost from the grooves of
the bowl.

CASELLA CEL's in house service department
offers a comprehensive range of repair and
calibration services, designed to effect a fast
and efficient back up for all our products. The
service department is operated under the
scope of our BSI registration for products
manufactured by us. We will however,
undertake the repair of other manufactures
equipment.

For further information please contact the
service department at our Bedford
headquarters. We will be happy to provide
quotations for individual repairs or provide
annual maintenance under contract.

CASELLA CEL LIMITED
Regent House
Wolseley Road
Kempston
Bedford
MK42 7JY
Telephone: [phone]
Facsimile: [phone]
E-mail: [e-mail]
Webpage: http://www.casella.co.uk

9. TECHNICAL INFORMATION

9.1 Specification

Adjustment for latitude: 0 to 65
Sphere: 101.6 mm dia (±1.3 mm)
Focal length for Sodium D light: 74.9 mm ±0.25 mm
Dimensions: 240 x 187 x 165 mm
Weight: 4.3 kg

9.2 Ordering Information

Tropical - for latitude 0 to 45
Temperate - for latitude 45 to 65

9.3 Accessories And Spares

One years supply of cards (BMO pattern) for use in latitudes up to 65
200 summer cards (No 6730) long curved
200 winter cards (No 6731) short curved
100 equinoctial cards (No 6732) straight
Transparent template for measuring length of trace: M114041

The contents of this manual are subject to change without notice.

o

N or S (cards not included): 102271D

o

N or S (cards not included): 102270D

ALTERATION WITHOUT NOTICE

o

N or S after selecting correct model

o

N or S: M107901

SUNSHINE RECORDERS

CAMPBELL STOKES PATTERN

User Instructions

HB3190-04

COPYRIGHT

The copyright in this document is vested in CASELLA CEL LIMITED. The contents of this

document must not be used for purposes other than for which it has been supplied or reproduced

1. INTRODUCTION

The Casella Campbell Stokes Sunshine
Recorder is manufactured to a design based
on British Meteorological Office (BMO)
specifications. It is designed to measure the
duration of visible sunshine for one day and
uses the intensity of the Sun's rays to burn a
trace on to a recording card.

The instrument measures only the
sunshine, for
would require a solarimeter.

The sphere is made from well-annealed
optical glass and the card on which sunshine

or disclosed wholly or in part without the prior written permission of

intensity

measurements you

CASELLA CEL LIMITED.

hours are recorded is inserted into the base of
the unit. Each card is marked with hourly
intervals and an optional transparent plastic
template is also available to help measure the
curved trace more accurately.

The instrument is fully adjustable for operation
at different geographical latitudes and levelling

duration

of

screws on the base ease installation.
Two versions of the sunshine recorder are

available, depending upon latitude, please see
Ordering Information for more details.

Side 2 CAMPBELL STOKES SUNSHINE RECORDER

User Instructions

Side 3

CAMPBELL STOKES SUNSHINE RECORDER
User Instructions

Side 4

2. PRINCIPLE OF OPERATION

A glass sphere is used to
focus the Sun's rays to an
intense spot in order to burn
a trace on to a heat sensitive
recording card. As the Sun
moves across the sky, the
spot moves across the card
burning a trace, when the
Sun is obscured the trace is
interrupted.

The sphere is made from
colourless optical glass and is
clamped in a metal arc. Also
attached to the arc is a metal
bowl of spherical section,
which is grooved on the
inside to hold the recording
cards. It is positioned at the
correct focal length from the
sphere to ensure burning of
the trace.

Different instruments are available depending
upon the latitude of the recording station.

o

0-45

North or South - Tropical

o

45 - 65

North or South - Temperate

SPHERE
CLAMP

BOWL

LEVELLING
FOOT

Figure 1: General arrangement of the sunshine recorder

3. RECORDING CARDS

The cards have been treated to char rather
than burn and to reduce the amount they
swell if they get wet.

When the Sun's altitude changes with the
seasons the Sun's image travels up and down
the bowl, so that three different types of sun
card are required.

As the position of each card changes within
the bowl, three pairs of overlapping grooves
have been cut on the inside of the bowl. The
grooves overlap so that the burn does not run
close to the edge of the recording card before
the next seasonal card.

Figure 2 shows the position of each of the
seasonal cards within the bowl.

Figure 2: Position of sun cards in the bowl

FIXED SPHERE
CLAMP

LATITUDE
SLIDE CLAMP

SUB-BASE

MAIN BASE

The only difference between the versions is
the shape of the bowl.

The arc is mounted on a grooved slide, which
enables the bowl to be set to the latitude of
the recording station.

Equinoctial

Winter

Summer

4. INSTALLATION

4.1 Access to Sun Rays

The Sun's rays must have unobstructed
access to the instrument in all seasons and at
all times of the day. Due to the low intensity
of the Sun's rays at sunrise and sunset, the
only exceptions are obstacles whose height
does not exceed 3

o

above the horizon.

Because of the need for unobstructed
sunlight, the roof of a building is often a
convenient site. However, if the building is
too high, it is possible for the roof to obscure
the Sun's rays after Sunrise and before

5. ADJUSTMENT

5.1 Levelling

This is achieved by adjusting the bottom nuts
(below the sub-base of the instrument) and
using a spirit level.

1. Slacken the nuts above and below the sub
base. See Figure 3.

2. Level using the bottom nuts.

3. First level in an East / West direction.

To help levelling, set the latitude to 0
Tropical or 52

o

for Temperate installations,

then lay the spirit level across the bowl.

4. Then level in a North / South direction,
placing the spirit
level on the flat
machined part of
the sub-base.

5. When you have
levelled the
instrument,
tighten the top nuts
finger tight.

If the instrument is
not level in an East /
West direction the
trace will burn at an
angle across the
card.

Figure 4: Rotation of the sub-base for North / South orientation

o

for

N/S

NOON LINE

Sunset, thus preventing the measurement of
a full days sunshine.

4.2 Mounting

The instrument should be mounted on to a
rigid warp free surface at a convenient height
to read and change sun cards, e.g. on a brick
pillar, with a wooden top.

Point the instrument in a southerly (northerly)
direction, within ±10

o

and secure the main
base to the mounting surface usually wood
(25 cm square).

TOP NUT

BOTTOM NUT

MAIN BASE

SUB-BASE

Figure 3: The Sub-base

5.2 North South Orientation

Using the mid-point (noon line) on the bowl,
align the instrument to face due South in the
Northern Hemisphere and due North in the
Southern.

1. Adjust the instrument by rotating the
sub-base.

If using a compass remember to take
magnetic variation into consideration. See
Figure 4.

2. When aligned, tighten up the top nuts.

You can also use time to set the instrument.
For example at 12 p.m. (G.M.T), 0

o

longitude,
the Sun's image will fall
on the bowl's noon line
when pointing due
South.

ARC

For other longitudes
local noon times need
to be calculated.

5.3 Setting
the Latitude

The bowl must be set to
the correct latitude for
the station.

Figure 5: Position of the arc clamping nut

6. DAILY ADJUSTMENT

Where possible, the cards should be changed
after sunset so that each card has a record of
one day's sunshine. If this is not possible
care must be taken with the dates, to keep
each day's sunshine correct.

When inserting a new card make sure that the
noon line on the card lines up with the noon
mark on the bowl.

On the back of each card, date ranges are
given for when they are to be used in both the
Northern and Southern hemispheres as well
as spaces for date etc. At certain latitudes it
is necessary to trim the cards to the specified
dotted line. This ensures that the Sun's rays
are not obscured by the edge of the card at
Sunrise and Sunset.

Difficulty may be experienced in removing the
recording card from the bowl when wet. Do
not try to force the card as it may tear. With a

1. Undo the nut beneath the arc support, using
the tommy bar provided.

2. Set the latitude by aligning the engraved
latitude marks with the arrowhead.

3. Tighten the nut while making sure that the
arc does not slip. See Figure 5.

5.4 Fitting the Sphere

The sphere is clamped into the arc using two
knurled head screws.

One of these screws is locked into position at
the factory, so when the sphere is clamped in
place it is already correctly aligned.

ARC CLAMPING
NUT

sharp blade cut as close to the grooves as
possible, parallel to the length of the card.
The remaining card in the groove can be
removed with a pointed stick or other soft
material.

The glass sphere should be kept clean using a
chamois leather or other non-scratching
material. It is also important to keep the
grooves clean and to remove any snow or
frost immediately.

When changing the cards, note the position
and angle of the burn, if it has not run parallel
to the edge of the card, the instrument should
be adjusted. Occasionally while the Sun is
shining, check to see that the burn is being
produced at the correct time and adjust if
necessary.

The instrument can be upset only by
someone moving it and not during normal use.