BISL 04-Weather and Climate

72 METEOROLOGY WWEATHER AND CLIMATE 73

Mobile Satellites

M

eteorological satellites, which have been orbiting the Earth for more than 30 years,

are an indispensable aid to scientists. Along with the images generated by these

instruments, meteorologists receive data that can be used to prepare weather

bulletins. These reports, circulated via the mass media, allow people all over the world

to know the weather forecast. Moreover, the most advanced satellites are used to

study the characteristics of phenomena such as tropical cyclones (hurricanes,

cyclones, and typhoons).

POLAR ORBIT

28,400 miles

(45,700 km)

TWO ORBITS

PER DAY

190 miles per

second (305

km/sec)

is the velocity of a

polar satellite at

an altitude of 560

miles (900 km).

EQUATOR EQUATOR

Transmitting

antenna

Receiving

antenna

X- ray

sensors

Telemetry

antenna

Log periodic

antenna

Image

reception

Magnetometer

UHF antenna

Solar

panels

Array

drive

NOAA-12 NOAA-14

NOAA-15 METEOR 3-5

GOES 8 GOES 9

METEOSAT-7 GMS

Images, Yesterday

and Today

The TIROS satellites (Television and

Infra-Red Observation Satellite) of

the 1960s provided the first images of

cloud systems. The modern GOES

satellites (Geostationary Operational

Environmental Satellites), which take

more precise time and space

measurements, provide higher-quality

images of clouds, continents, and

oceans. They also measure the humidity

of the atmosphere and the temperature

at ground level.

represents infrared emissions or heat from

the clouds and from the Earth's surface.

Objects that are hotter appear darker.

INFRARED IMAGE

They are composed of infrared

images (which permit

differentiation of high and low

clouds) and visible-light images

(which measure the reflectivity of

each climatic subsystem).

COMBINED IMAGES

Oceans and continents have low

albedo and appear as darker

areas. Areas with high albedo, in

contrast, are clear and bright.

VISIBLE IMAGE

Geostationary

They orbit the Earth above the Equator

and are synchronized with the Earth's

rotation—that is, as they orbit the Earth,

they are always over the same geographic

point on the Earth's surface.

Polar Orbit

They orbit from pole to pole with a

synchronized period. As they move in their

orbits, they scan swaths of the Earth's

surface. They pass over any given point

twice a day. Their operational lifetime is

approximately two years.

GOES EAST

Orbital altitude

Weight

Launch date

Orbit

22,370 miles (36,000 km)

4,850 pounds (2,200 kg)

2001

75°

12 feet

(3.6 m)

88 feet

(26.9 m)

AREA OF LEAST

HEAT EMISSION

AREA OF GREATEST

HEAT EMISSION

YELLOW

Low clouds

DARK ZONES

Low reflectivity

ORANGE

Dry and

mountainous

WHITE

High clouds

GREEN

Vegetation

CLEAR ZONES

High

reflectivity

ACTIVE POLAR SATELLITES ACTIVE GEOSTATIONARY SATELLITES

CHARACTERISTICS

ORBITAL ALTITUDE

ROTATIONAL VELOCITY

ORBITAL PERIOD

22,300 miles (35,900 km)

100 RPM

24 hours

GEOSTATIONARY

ORBIT

22,245 miles

(35,800 km)

ACCOMPANYING

THE EARTH

1,100 miles per second

(1,770 km/sec)

The velocity necessary

to remain fixed over one

point on the Earth

Solar

sail

Sensors