21.3 Weather InstrumentsCHAPTER 21 – WEATHER

What do Scientists look for in weather?

Scientists look for patterns… Patterns are used to make predictions for future occurrences based on those patterns Meteorologists gather data about atmospheric pressure, humidity, temperature, wind speed, and precipitation with instruments Using these instruments in order to analyze & predict the weather. Meteorologists have not attempted to control forms of precipitation!

Measuring the Lower Atmosphere

Thermometer: liquid sealed in a vacuum tube that expends when heatedBc of tubing, liquid expands up in a thermometer when temp. rise.

Electrical thermometer: when temp rises, electrical current increases.

Thermistor: electrical thermometer useful when temp changes occur rapidly…can senses smallest changes!

Temperature

Measuring the Lower Atmosphere Cont.

Air Pressure:

Barometer: measures air pressure. When a front approaches, a drop in air pressure occurs.

Wind Speed:

Anemometer: measures wind speed using an electrical signal generated by rotating cups.

Wind Direction:

Wind Vane: arrow bar on a pole—tail catches the wind. Direction can be compass (N, NW, S, etc.)

Radiosonde: instrument package that measures humidity (hygrometer), pressure (barometer), and temp.carried by a helium filled balloon. Wind speed/direction are measured by balloon’s path, balloon eventually bursts and radiosonde parachutes back to Earth.

Measuring the Upper Atmosphere *tracking global weather patterns

Radar: Radio Detection and Ranging [Newest—Doppler] Uses radio waves to determine velocity & location of water in the atmosphere.

Measuring the Upper Atmosphere Cont.

Weather Satellites: uses cloud sequence images to measure wind speed/directioninfrared to measure temp data and also measures ocean wave height, flow of ocean currents, & even soil moisture conditions in remote areas of Earth.

Computers: Solutions of complicated mathematical equations – with abilities to describe the atmosphere behaviors. Store incredible amounts of historical data & weather records

Additional Info to Know… Station Models are used by meteorologists…As a pattern system of symbols to represent the data collectedAt a particular observing station Recorded on a weather map

Watches and Warnings are meant to decrease destruction and save lives. Severe Weather Watch: conditions are ideal for a severe weather event. Severe Weather Warning: severe weather has already been spotted.