Gathering Weather Data

Gathering Weather Data

​To predict the weather, scientists must first gather information about conditions in the Earth's atmosphere.

​Predicting the Weather

Open Ended

If you studied the weather, what information would you want to gather?

• Humidity

• Wind Speed & Direction

• Temperature

• Precipitation

• Air pressure

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Factors Meteorologists study

Open Ended

What tools can you name that are used to measure weather information?

• measures wind speed

• Wind pushes the inside of the cups, so they rotate.

• The stronger the wind is, the faster the cups spin.

Anemometer

• measure wind direction

• often on roof tops

• wind pushes the "tail" until the arrow turns & points in the direction of the wind

Wind Vane

• measures air pressure

• as air pressure changes, the air inside expands or contracts

Barometer

• Measures humidity (moisture in the air)

• Often consists of two thermometers which measure and compare temperature when wet and when dry

Psychrometer

• Measures air temperature

• A common type uses a glass tube filled with liquid that expands and rises as it warms.

• Marks on the tube may measure in Fahrenheit or Celsius.

​​Thermometer

Open Ended

Meteorologists make predictions based on the weather data that is gathered.

What do you think a change in air pressure would mean?

• If air pressure drops, a low-pressure air mass is moving into the area.

• A low-pressure system usually indicates rainy or snowy weather is coming.

• Very cloudy, overcast skies are also a result of low pressure systems.

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​Changing Air Pressure - Low

• If air pressure rises, a high-pressure system is moving into the area.

• This indicates fair weather is on the way.

• The air is "heavy" and sinks; this makes things stable.

• Think sunny skies and calm weather!

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​Changing Air Pressure - High

Open Ended

Why would we need to know the speed and direction of winds?

The speed and direction of winds can be used to predict how damaging a coming storm might be and from where it is coming.

Open Ended

Why are we concerned with humidity?

• Humidity refers to the amount of moisture present in the air.

• An increase in humidity means there is more moisture in the air.

  • This can result in cloud formation and precipitation.

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Humidity

Open Ended

How does air temperature affect weather?

• Air temperature determines how much water vapor the air can hold.

  • Warmer air holds more water vapor than colder air.

  • Also, evaporation happens more quickly at higher temperatures.

  • As warm, wet air cools, the water vapor may condense and form clouds, form fog, or fall as precipitation.

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Air Temperature

Open Ended

What would a low-pressure air mass combined with high humidity, cooler temperatures, and strong winds signal?

A low-pressure air mass with high humidity, cooler temperatures, and strong winds will signal a storm is coming.

Multiple Choice

As the air warms, the liquid in this instrument expands and rises. What weather instrument does this describe?

• wind vane

• evaporator

• anemometer

• thermometer

Multiple Choice

When a report states that the air pressure is rising in your area, what instrument did a meteorologist likely use to get this information?

• barometer

• thermometer

• psychrometer

• anemometer

Multiple Choice

What will happen if humidity increases until the air cannot hold anymore water vapor?

• Weather conditions will stay the same.

• More water will evaporate from any nearby bodies of water.

• The water vapor will move as wind to an area of lower humidity.

• Clouds or fog will form, and precipitation may occur.

Multiple Choice

What kind of weather conditions should you expect when the air pressure drops suddenly?

• sunny, fair weather

• storms, with precipitation

• morning fog, then fair weather

• high temperatures and low humidity