Video news journalism covers a wide spectrum of visual/sound reports which use a number of camerawork conventions. A loose classification separates hard news stories, which aim to transmit an objective, detached account of an event (e.g. a plane crash), from those soft news stories which incline more towards accounts of lifestyle, personality interviews and consumer reports. Acceptable camera technique and style of shooting will depend on content and the aim of the report. For example, a politician arriving to make a policy statement at a conference will be shot in a fairly straightforward camera style with the intention of simply ‘showing the facts’. An item about a fashion show could use any of the styles of feature film presentation (e.g. wide angle distortion, subjective camerawork, canted camera etc.). The political item has to be presented in an objective manner to avoid colouring the viewer’s response. The fashion item can be more interpretative in technique and presentation in an attempt to entertain, engage and visually tease the audience. A basic skill of news/magazine camerawork is matching the appropriate camera-work style to the story content. The main points to consider are:
producing a technically acceptable picture (see Section 6, Working on location)
an understanding of news values and matching camerawork style to the aims of objective news coverage
structuring the story for news editing and the requirements of news bulletins/magazine programmes
getting access to the story and getting the story back to base.
What Makes a Story News?
There is no universally acceptable definition of news. A wide diversity of stories can be seen every day as the front page lead in newspapers. There appears to be little consensus as to what is the main news story of the day. The only generalization that can be made in television is that news is usually considered to be those topical events that need to be transmitted in the next immediate news broadcast. Access, rapid working methods, a good appreciation of news values and the ability to get the material back, edited and on the air are the main ingredients of ‘hard news’ camerawork. There is no specific agreed technique in camera/recorder news coverage although there are a number of conventions that are widely accepted. People almost always take precedence over scenery as the principal subject of news stories. Faces make good television if they are seen in context with the crisis. Where to position the camera to get the shot that will summarize the event is a product of experience and luck, although good news technique will often provide its own opportunities. A news story can quickly lose the interest of its potential audience if it does not, at some point in the report, feature a person.
One crucial requirement for news coverage is to get to where the story is. This relies on contacts and the determination to get where the action is. Civil emergencies and crises are the mainstay of hard news. Floods, air/sea rescue, transport crashes, riots, fire and crime are news events that arise at any time and just as quickly die away. They require a rapid response by the cameraman who has to be at the scene and begin recording immediately before events move on. Equipment must be ready for instantaneous use and the cameraman must work swiftly to keep up with a developing story.
In some countries or regions, access may be denied unless you are in possession of a certified police pass, press pass and in the case of some civil disasters the appropriate safety clothing. Inform the police and/or the appropriate authority for all day use of a street or public place for location recording. Security clearance is almost always required in order to enter military, naval and other restricted access sites.
Returning the Material
Getting the news material back to base can be by transport, land line, terrestrial or satellite link or foldaway SNG equipment. The important thing is to get the material to base fast with supporting information (if a reporter is not at the location) in a form (the cassette clearly marked) that can be rapidly edited. Use a separate tape for the reporter’s voice-over and a 5-minute tape for cutaways to speed up editing. Use a new tape for each story so that the stories can be cut independently if required.
Record or Interpretation
One basic convention is the distinction between news camerawork as a record of an event and camerawork as an interpretation of an event.
The record of An Event: Information shots are specific. They refer to a unique event – the wreckage of a car crash, someone scoring a goal, a political speech. They are often non-repeatable. The crashed car is towed away, the politician moves on. They are the guts of a news story and if the crucial shot is missing, the story will lose impact and significance. The item will deteriorate into an account of what has happened, but can no longer be seen.
Interpretative Shots: Interpretative or decorative shots are nonspecific. They are often shot simply to give visual padding to the story. A typical example is a shot of an interviewee walking in a location before an interview. This shot allows the dubbed voice-over to identify who the interviewee is and possibly their attitude to the subject. The shot needs to be long enough to allow information that is not featured in the interview to be added as a voice over. The interviewee leaves frame at the end of the shot to provide a cutting point to the interview. Have the interviewee medium-close-up facing in the same direction as the preceding walk to the interview.
There is a basic dilemma in news bulletins between objectivity and the need to engage and hold the attention of the audience. As the popularity of cinema films has shown, an audience enjoys a strong story that involves them in suspense and moves them through the action by wanting to know ‘what happens next’? This is often incompatible with the need for news to be objective and factual. The production techniques used for shooting and cutting fiction and factual material are almost the same. These visual story telling techniques have been learned by the audience from a life time of watching fictional accounts of life. The twin aims of communication and engaging the attention of the audience apply to news as they do to entertainment programmes.
A television news report has an obligation to separate fact from opinion, to be objective in its reporting, and by selection, to emphasize that which is significant to its potential audience. These considerations therefore needed to be borne in mind by a potential news cameraman as well as the standard camera technique associated with visual story telling. Although news aims to be objective and free from the entertainment values of standard television story telling (e.g. suspense, excitement etc.), it must also aim to engage the audience’s attention and keep them watching. The trade-off between the need to visually hold the attention of the audience and the need to be objective when covering news centres on structure and shot selection.
Communication and Audience Involvement
Communicate in an objective style without unduly ‘colouring’ the item.
Identify the main ‘teaching points’ the audience should understand, i.e. What is this item about? What is the crucial point (or points) the audience should grasp?
Find the appropriate method of presentation (shots, structure, narrative) to hold the audience’s attention.
Involve the viewer by pace, brevity (e.g. no redundant footage) and relevance (e.g. How does it affect me? Can I empathize with this situation?).
Capture the attention by arresting images supported by lucid and appropriate narration and exposition.
Although news is often an unplanned, impromptu shoot, the transmitted item should end up as a seamless flow of relevant shots spliced together to meet the standard conventions of continuity editing.
Balance the shooting ratio (too much footage, and it cannot be edited in the time scale available) against sufficient coverage to proved flexibility as the story develops over time, to allow the editor to cut the item down to the required running time.
What Increases Subjectivity?
Subjectivity is increased by restaging the event to serve the needs of television (e.g. re-enacting significant action which occurred before the camera arrived), and by selecting only ‘action’ events to record. For example, violent demonstrations as opposed to discussion about the subject, or a police car chase rather than routine police work of computer checks through a data base. Also the use of standard ‘invisible’ technique editing can distort an objective report (e.g. the compression of time, selecting only action aspects of the story).
Editing is selection and can produce a partial account of an event. For example, a football match can be cut down to a 30-second ‘highlights’ report of the match and make it a great deal more exciting than the match witnessed by the crowd at the stadium.
Although there is an attempt to avoid these ‘entertainment’ aspects of story telling in news reportage, they are often unavoidable due to the nature of the news item or the demands of attracting viewers.
Like news, magazine items often attempt to capture spontaneous action and present an event objectively. But whereas news is generally topical information of the day, shot on the day, magazine themes and issues are shot over a period of time. A news item may have a duration of less than thirty seconds while a ‘feature’ report can run for three to five minutes. All these factors have a bearing on the camera techniques that are used on the different genres.
News attempts to emphasize fact rather than opinion, although journalistic values cannot escape subjective judgements. Feature items can use fact, feeling and atmosphere, argument, opinion, dramatic reconstruction and subjective impressions which can be very similar to standard feature film story telling. Non-topical items can be filmed and edited, and often shelved as stand-by or they can be used to balance the programme when required. Without the immediate pressure to transmit, they can have more considered post production (e.g. the addition of music and effects).
Diary Events
Many topics that are featured in news and magazine programmes are known about a long time before the event occurs. These ‘diary’ events allow forward planning and efficient allocation of people and time. They also provide the opportunity for advanced research and a location shoot can be structured and more considered.
Even if a ‘diary’ item is considered to be predictable and straightforward, be flexible on the day and be prepared for the unexpected (e.g. an unexpected demonstration by protesters in the middle of a VIP tour).
Abstract Items
Many issues dealt with by factual programmes are often of an abstract nature which at first thought have little or no obvious visual equivalent. Images to illustrate such topics as inflation can be difficult to find when searching for visual representations. Often the solution, with the above example, is to fall back on clichéd shots of shoppers and cash tills with a great deal of voice-over narration providing the explanations.
Whatever the nature of a news story, there must be an on-screen image, and whatever is chosen, that picture will be invested by the viewer with significance. That significance may not match the main thrust of the item and may lead the viewer away from the topic. For example, a story about rising house prices may feature a couple looking at a house for sale. To the viewer, the couple can easily, inadvertently, become the subject of the story. Consider the relevance of all details in the shot, and have a clear idea of the shape of the item, its structure, and what it is communicating.
Some news items are abstract topics that have no concrete image. Appropriate visual ‘wallpaper’ needs to be shot to support voice-over information. For example, shots of high street shoppers to accompany a news story about inflation.
A news bulletin has a limited transmission time to present the news of the day. There is always constant pressure, to reduce the running time of a topic. This should be borne in mind when shooting an item. Provide cutaway shots to allow the journalist/editor to compress the actual time of an item to fit the duration allocated in the programme (see Section 8, Editing).
The editor only has a certain amount of time to cut the item. The cameraman can help by remembering:
to shoot with editing in mind and for hard news, keep shooting ratios low for a fast turnaround in the edit suite.
it is important to be brief and provide only significant shots for news as tape has to be reviewed in real time before being cut
with a hard news story, help to reduce the amount of shuttling the editor will be involved in and where ever possible, shoot in sequence and shoot interviews on one tape and cutaways on a second tape
record each story on a separate tape to allow a separate editor (if required) to work on each story
record only those shots that are significant and best sum up the essence of the story. Each shot must serve a purpose in telling the story
the viewer will require a longer on-screen time to assimilate the information in a long shot than the detail in a close shot. Provide more detail than geography shots or scene setting
avoid long panning or zooming shots. News stories are cut down to the essentials and need the flexibility of editing at any point in the shot
it is more difficult to edit moving shots than static shots
provide a higher proportion of static shots to camera movement. It is difficult to cut between pans and zooms until they steady to a static frame and hold
use short pans (no more than 2 seconds long) to inject pace into story
moving shots require more perceptual effort to understand than static shots; therefore include more close, static shots than ones with camera movement
use the 5 second module for news which is:
10 second hold at the start of the pan or zoom
5/10 second camera movement
5/10 second hold at the end of the pan or zoom
this provides the editor with three different shots.
Check continuity and avoid shooting interviews against a moving background which could ‘jump’ when edited (e.g. a background to a 10-minute interview of a crowd leaving a stadium after a match which when edited may use comment from the start and the end of the interview and produce a mismatch with a background).
A substantial change in shot size or camera angle/camera position are needed for shots intending to be intercut.
Provide relevant but non-specific shots so that voice-over information (to set the scene or the report) can be dubbed on after the script has been prepared.
Remember to provide adequate run-up time before significant action to allow for a stable shot/syncs for editing.
Use ‘record run’ time code rather than ‘time-of-day’ wherever possible.
Provide accurate information on cassette or add v/o on tape to identify specific people or events (e.g. on a courtroom exit, identify any significant people in the shot).
Remember that a casual title given to the item at the morning editorial meeting may change by transmission. Provide a brief description of content on the cassette.
Have in mind a structure for the shots you provide to allow the editor to create pace, shot variety and fluid continuity.
Hard news by its nature is seldom, if ever, pre-scripted and therefore material is recorded without a written plan. The cameraman with the journalist, needs to shoot with editing in mind and think in terms of a structure for the shots provided. A series of shots have to be meaningfully edited together and this relies on the cameraman anticipating edit points. As it has been emphasized, nothing is more time consuming than an attempt to edit a pile of cassettes of ill-considered footage into some intelligent and intelligible form. To avoid this, the editor requires from the cameraman maximum flexibility with the material supplied, and the nucleus of a structure.
Every shot is recorded for a purpose; that purpose should fit the outline of a possible structure. No shot can exist in isolation. A shot must have a connection with the aim of the item and its surrounding shots. It must be shot with editing in mind. This purpose could be related to the item’s brief, script, outline, or decided at the location. It could follow on from an interview comment or reference. It could be shot to help condense time or it could be offered as a ‘safety’ shot to allow flexibility in cutting the material.
Definition of Structure
Structure is arranging the building blocks – the individual unconnected shots, into a stream of small visual messages that combine into a coherent whole. Before a shot is recorded three basic questions need (approximate) answers:
- The proposed running time of the item in the programme.
- When will it be broadcast (i.e. how much time is available for shooting, returning the material to base, and then editing/sound dub)?
- How many locations can be realistically used?
Most news items will not be scripted. There may be a rough treatment outlined by the presenter or a written brief on what the item should cover but an interview may open up new aspects of the story. Without preplanning or a shot list, the shots provided will often revert to tried and trusted formulas. A safe rule-of-thumb is to move from the general to the particular – from wide shot to close up. Offer a general view (GV) to show relationships and to set the scene and then make the important points with the detail of close-ups. The cameraman has to provide a diversity of material to provide a cutting point. Lastly, the structure of a television magazine item is often unplanned, but a location shoot for a two-minute item that results in ten twenty-minute cassettes with no thought to its eventual structure other than a misguided belief that it can all be sorted out in editing will usually mean that the time saved on location avoiding structuring the treatment will be more than quadrupled and lost when the editor attempts to bring order to the chaos he/she is presented with.
An appropriate shot will fulfil one of the following functions in the structure of the piece:
It emphasizes the essence of the principal subject.
It provides variation in shot size.
It gives added prominence to the selected subject.
It provides more information about the subject.
It provides for a change of angle/size of shot to allow unobtrusive intercutting.
It allows for variety of shot and shot emphasis.
It allows variety of pace by camera or artiste movement.
Unusable Shots
Many shots are immediately eliminated because:
they are not relevant to the story
they are too short
significant action has begun before recording is stable
camera movement is too slow resulting in the duration of the shot becoming too long for the news item (see the 5-second module for news on page 210, Condensing time)
the speed of the camera movement conflicts with the pace of the story
continuity mismatch
size mismatch
technical imperfections
out of focus
shaky
badly framed
conflicts with background
difficulty with time code (e.g. edit controller using ‘time-of-day’ time code cannot find anticipated code on a rollback for a run-up to an edit – see Assemble edit, p. 142)
As we have emphasized, the strongest way of engaging the audience’s attention is to tell them a story. Structuring a report is determining what to tell the audience, and when. Cause and effect or question and answer are convenient ways of holding the viewer’s interest over time. A factual story can be created by building up a series of details rather than broad generalizations. The crucial decision by the journalist and the cameraman is to determine which visual details are chosen to best illustrate the main theme.
Visual Communication and Structure
Creating a structure out of the available material will tell a story, present an argument or provide a factual account of an event (or all three). It starts with a series of unconnected shots which are built into small sequences. These are then grouped into a pattern which logically advances the account either to persuade or to provide sufficient information leaving the viewer to draw their own conclusion. Usually the competing point-of-views are underlined by the voice-over but a sequence of strong images will make a greater impact than words. A necessary element to link the selected details is some kind of thread or motif which is easily followed and guides the viewer through the sequence of shots. For example, an item on the widespread colonization of the English countryside by Japanese knotweed, could be structured by walking the reporter and ‘expert’ along the bank of an infested stream. The walk could be shot starting at a point with a clear stretch of stream, then passing a stretch of weed, and then ending on remedial work being done to clear the stream. Each stage of the walk could be accompanied by actuality sound or voice-over dubbed in editing plus the required cutin to close-ups relating to the interview comments. The walk is the thread that links the item together. Although this a fairly straightforward treatment, it does need some thought and preparation by the cameraman when constructing the shots (i.e. shoot with a structure in mind), so that normal continuity editing technique can be applied. To inject interest, and to avoid a predictable pattern to an item, not all structures need to lay the events of a story out in simple chronological order.
Any activity must be filmed to provide a sufficient variety of shots that are able to be cut together following standard editing conventions (e.g. avoidance of jump cuts, etc.) and to ensure that there is enough variety of shot to allow some flexibility in editing. Just as no shot can be considered in isolation (what precedes and what follows always has an effect), every sequence must be considered in context with the overall aims of the production.
Probably the most frequent location shot in news, magazine and other topical programmes is the journalist/presenter speaking straight to camera. It is usually staged so that the keynote image of the item (Houses of Parliament, White House etc.) is the background to the shot.
If it is shot during the day, then care must be taken to find a camera position that allows the reporter to speak to the camera comfortably whilst allowing an exposure balanced between face and background ‘topic’. This can often be achieved with the sun at the three quarter back position doubling as backlight and ‘side kicker’ to the face to provide some modelling. A reflector may be needed to lift the unlit side of the face depending on the intensity of the sun
At night the exposure balance is between the background floodlit building and the foreground presenter. A battery light needs to be filtered or the camera distance adjusted so that a good overall exposure is achieved between face and building.
The other point to consider is background traffic noise and, in a public place, freedom from the occasional eccentric passer-by who decides to stand in the background and divert attention from the presenter. With most public buildings, there is usually one favoured viewpoint marked out by ‘tripod marks’ from countless camera crews that have been there before.
The interview is an essential element of news and magazine reporting. It provides for a factual testimony from a participant or witness to an event. Interviews can be shot in a location that reinforces the story and possibly gives more information to the viewer about the speaker (e.g. office, kitchen, garden, etc.).
Exterior interviews are easier to stage when there is a continuity of lighting conditions such as an overcast day or where there is consistent sunshine. The natural lighting will have to cater for three shots and possibly three camera positions – an MCU of the interviewee, a similar sized shot of the interviewer and some kind of two-shot or ‘establishing’ shot of them both. If it is decided to shoot the interview in direct sunlight, then the interview needs to be positioned with the sun lighting both ‘upstage’ faces (i.e. the camera is looking at the shaded side of the face) using a reflector to bounce light into the unlit side of the face. The position of the participants can be ‘cheated’ for their individual close shots to allow a good position for modelling of the face by the sun. Because of the intensity of sunlight and sometimes because of its inconsistency, it is often preferable to shoot the interview in shade avoiding backgrounds which are in the full brightness of the sun.
Staging an Interview
An interview is usually shot using a combination of basic shots which are:
an MS, MCU or CU of the interviewee
a matched shot of the interviewer asking questions or reacting to the answers (usually shot after the interview has ended)
a two-shot which establishes location and relationship between the participants or an over-the-shoulder two-shot looking from interviewer to interviewee.
After the interview has been shot, there is often the need to pick up shots of points raised in the interview (e.g. references to objects, places or activity, etc.). In order for normal ‘invisible’ editing to be applied, the shots should match in size and lens angle between interviewee and interviewer. Sometimes it is necessary for the cameraman, who may be first on the scene of a civil disaster, to get eyewitness statements if a journalist has yet to arrive and there is the possibility that people may leave the scene of the incident. People respond and give more information if they are asked an ‘open’ question. This is usually an invitation to give an account or description of an event or what happened to them. It can be in the form of ‘Tell us what happened to you’ or ‘What did you see?’. Some questions such as ‘Did you see the crash?’ can be answered in a single word, ‘Yes’ or ‘No’. These are called ‘closed’ questions. They close down possible responses from the interviewee. Look for questions that will provoke the fullest response from the witness or participant.
Agree with the journalist that he/she will start the interview when cued (or take a count of 5) when the camera is up to speed.
It is useful for editing purposes to precede the interview with details of name and title of the interviewee.
Remind the reporter and interviewee not speak over the end of an answer.
Do not allow interviewee to speak over a question.
Change shot size on question if needed.
Do cutaways immediately after interview to avoid changes in light level.
Always provide cutaways to avoid jump cuts when shortening answers.
Watch that the background to an establishing two-shot is from a different angle to any cutaway shot of the subject. For example, a wide shot of the ruins of a fire is not used later for the background to an interview about the fire. This causes a continuity ‘jump’ if they are cut together.
Think about sound as well as picture, e.g. avoid wind noise, ticking clock or repetitive mechanical sound, etc., in background.
Depending on the custom and practice of the commissioning organization that cut the material, use track 1 for v/o and interview, and use track 2 for effects.
Iindicate audio track arrangements on the cassette and put your name/story title on the tape.
Going Live
The ability to broadcast live considerably increases the usefulness of the camera/recorder format. As well as providing recorded news coverage of an event, a single camera unit with portable links can provide live ‘updates’ from the location. As the camera will be non-synchronous with the studio production, its incoming signal will pass through a digital field and frame synchronizer and the reconstituted signal timed to the station’s sync pulse generator. One advantage of this digital conversion is that any loss of signal from the location produces a freeze frame from the frame store of the last usable picture rather than picture break-up.
Equipment
Cameras with a dockable VTR can attach a portable transmitter/receiver powered by the camera battery in place of the VTR. The camera output is transmitted ‘line of sight’ to a base antenna (up to 1000 m) which relays the signal on by land line, RF link or by a satellite up-link. Other portable ‘line of sight’ transmitters are designed to be carried by a second operator connected to the camera by cable.
When feeding into an OB scanner on site, the camera/recorder operator can receive a return feed of talkback and cue lights, whilst control of its picture can be remoted to the OB control truck to allow vision control matching to other cameras. It can therefore be used as an additional camera to an outside broadcast unit. In this mode of operation it can supply recorded inserts from remote parts of the location prior to transmission. During transmission the camera reverts to being part of a multi-camera shoot. Unless there is very rapid and/or continuous repositioning, mount the camera on a tripod.
Communications
Good communications are essential for a single camera operator feeding a live insert into a programme. Information prior to transmission is required of ‘in and out’ times, of duration of item and when to cue a ‘front of camera’ presenter. A small battery-driven ‘off air’ portable receiver is usually a valuable addition to the standard camera/recorder unit plus a mobile phone.
Satellite news gathering (SNG) consists of a camera/recorder feeding into a small portable dish aerial transmitting a signal up to a satellite in geosynchronous orbit which relays the signal back to a base station. This allows live coverage of events from locations inaccessible to normal land line or terrestrial links equipment.
Ku-Band and C-Band
Whilst C-band satellite uplinks and downlinks share frequency bands allocated to common carrier microwave systems, Ku-band satellite systems have exclusive use of their allocated frequency band, and therefore are not restricted by sharing considerations. C-band satellites are limited to lower, downlink power levels to avoid interference with terrestrial microwave systems. Ku-band satellites have no such limitation and can operate at higher power within the limitations of the power source of the satellite. This generally permits the use of smaller downlink antennas in the Ku-band although Ku-band signal transmissions are subject to degradation from heavy rainfall, particularly in the tropics; C-band transmissions, however, suffer negligible attenuation when passing through belts of high rainfall.
Elevation Angle
The elevation of the path to the satellite above the horizontal (the look angle), is critical to establishing an SNG link. A low elevation angle of the satellite just above the horizon can cause problems (see orbital arcs opposite). Careful site selection is therefore important to ensure a clear line-of-sight to the designated satellite. The antenna requires protection against strong winds which could shift the antenna’s precise alignment to the satellite.
SNG Set-Up
The process involved in establishing an SNG link from location to a base station involves aligning the antenna onto the correct satellite using compass and azimuth bearings and if available, the transmitted beacon identification. Polarization is checked and the correct vision transmission frequency and communication transmission frequency is selected. The antenna signal radiation can damage electronic equipment (including camera/recorders!) and people, if they are in direct line of sight of the beam. Check for clearance before switching on the high-powered amplifier (HPA) to warm-up and then to stand-by. Contact the satellite operation centre (SOC) to confirm channel and booked time and seek permission to ‘come-up’ for line-up. Permission is given to transmit a clean carrier followed by a gradual increase in transmission power of colour bars and identification. Instant full power can damage the satellite transponder. Finally, check with base station that it is receiving a good strength signal.
In order that an SNG unit can continuously transmit an unbroken signal without constantly realigning its dish aerial, the satellite must be placed in an orbit stationary above the earth. This is achieved by placing the satellite in an orbit 22,300 miles from the earth where it is held in place by the balance between the opposing force of the gravity pull of earth against the centrifugal force pulling it out into space. Geosynchronous orbit (GEO) satellites revolve at the same rotational speed as the earth and appear stationary from the earth’s surface. Signals can be transmitted to and from them with highly directional antennas pointed in a fixed direction. It is the satellites’ fixed position in relation to earth that has allowed the growth of small, portable dish transmitters.
Orbital Arcs
The number and position of the satellites located in this orbital arc 23,300 miles above the earth, are regulated by a number of world-wide authorities. The satellites are positioned, after the initial launch, by a gas thruster which ensures they keep their position 2° from adjacent satellites. Frequencies used for communications transmission are grouped into Ku-band (10.7–18 GHz) and C-band
(3.7–4.2 GHz). The Ku-band is almost universally used for portable SNG service because the antennas are smaller for a given beam width due to the shorter wavelength, and the freedom from interference to and from microwave systems.
There are problems with transmission paths to satellites positioned close to the horizon and therefore some orbital slots are more favourable than others. A minimum elevation angle of 10° to 20° for Ku-band is required to avoid difficulty in clearing buildings, trees, and other terrestrial objects, atmospheric attenuation, and electrical noise generated by heat near the earth’s surface.