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Discover Climate: Activities from NOAA

Weather describes what is happening in the atmosphere over a short period of time (days or hours) at a specific 

place. Weather descriptions include temperature, humidity, 

winds, cloudiness, and atmospheric pressure. Climate is 

the average of these weather conditions over many years. 

The National Weather Service uses 30 years of weather 

measurements to calculate the average climate for a city, state, 

or region. An easy way to summarize the difference is “climate 

is what you expect; weather is what you get,” or “weather tells 

us what kinds of clothes to wear, climate tells us what kinds of 

clothes to buy.”

When scientists talk about climate change, they mean that there 

has been a significant change in the average or extreme (or 

both) climate conditions, and that this change has continued 

over a long period of time. We all know that climate conditions 

(air temperature, precipitation, and wind) change with the 

seasons. There are also natural cycles such as El Niño that cause 

climate conditions to be different from year-to-year. These 

differences are part of natural climate variability, but they are 

not the same as climate change.

Earth’s climate has changed many times in the past, and is 

changing now. Studies of tree rings show that Earth’s average 

temperature is now as warm or warmer than it has been for 

at least the past 1,300 years. Scientific weather observations 

from around the world show that average temperatures have 

increased rapidly during the past 50 years, especially in the 

Arctic region. In the past, climate change has happened over 

periods of decades to thousands of years. It is very unusual to 

have a rapid temperature change in only 50 years, because few 

natural processes affect climate this quickly. The rapid rate of 

20th century warming, and the increase above the millenium 

baseline in the absence of natural forcing, are consistent with 

the warming caused by increased greenhouse gases. One way 

that this is happening is that human activities are adding carbon 

dioxide to the atmosphere much more rapidly than natural 

processes can remove it. You’ll find out more about how carbon 

dioxide affects climate in Activity 6.

How It Works

An electric current is the flow of electrons through a conductor 

such as a wire. An electric circuit is a path for an electric current. 

One way to imagine an electric current is to think of water 

flowing through a pipe. The voltage of an electric current is 

the force of the current, similar to the pressure of the water in 

the pipe flowing through the imaginary pipe. As you may have 

guessed, voltage is measured in volts.

Resistance is a force that opposes the flow of an electric current. 

You can think of resistance as a valve or obstruction in the 

imaginary pipe. Resistance is measured in ohms; the more ohms, 

the higher the resistance. Resistors are electronic components 

that resist the flow of electric currents.

A thermistor is a type of resistor whose resistance changes 

when the temperature changes. When a thermistor is in an 

electric circuit, the voltage of the electric current changes 

when the thermistor’s resistance changes. We can measure the 

voltage of this type of circuit, and use this measurement to find 

the temperature of the thermistor. Compared to liquid-filled 

thermometers, thermistors are less expensive, more rugged, 

and do not require someone to look directly at them to get 

a temperature measurement. Because of these advantages, 

Activity 4: Climate, Weather...What’s the Difference?

What You Will Do: Make an Electronic Temperature Sensor

What You Will Need

Adult partner

1 – Multimeter capable of measuring volts, 

milliamps, and ohms (such as Extech 

MN35) 

1 – 9 volt battery 

1 – Battery snap (such as Radio Shack 270-

324)

1 – Resistor, 10K ohm, 1/2 watt (such as 

Radio Shack 271-1126)

1 – Thermistor, 10K ohm (such as Digi-Key 

490-4660)

2 – Clear glass jar, beakers or plastic cups, 

about 250 ml (8 oz) capacity

1 – Wire strippers

1 – Thermometer (such as Forestry Suppliers 

#89323; you may want to order two of 

these, since you will use them again for 

Activity 6; these thermometers have 

an aluminum case which makes them 

useful for field investigations as well as 

in your laboratory)

Speaker wire, 24 gauge, about 1 m (3 ft) 

(such as Radio Shack 278-1301)

Liquid electrical tape (from a boating supply 

store or hardware store)

Conductive Glue (keyword search “wire 

glue” to find suppliers; if you or your 

partner know how to solder, you can 

use solder and a soldering iron instead 

of conductive glue)

Needle-nose pliers 

Ice 

Hot water

Big Idea

Climate varies in space and time 

through both natural and manmade processes. 

(Climate Science Principle 4)
15 Climate Science Principle 4. Climate waries in space and time through both natural and man-made processes.

4. Climate, Weather...What’s the Difference?

thermistors are used in cooking appliances, indoor/

outdoor thermometers, doctors’ offices, fire alarms, 

refrigerators, wind turbines, weather balloons, 

aircraft, space vehicles, industrial facilities, and many 

other places where temperature measurement or 

control is needed.

How to Do It

1. Remove about 2 cm 

(1 in) of the insulation 

from both ends of the 

two wires in the speaker 

cable, and also from the 

two wires of the battery 

snap. Twist the strands of 

each wire so that they are 

tightly wrapped (Figure 1).

2. Connect the wires from one end of the speaker 

cable to the wires coming from the thermistor. 

Use a Western Union splice as shown in Figure 2.

3. Use a Western Union splice to connect one of the 

wires from the other end of the speaker cable 

to one of the wires coming from the resistor (it 

doesn’t matter which wire). 

4. Use a Western Union splice to connect the other 

wire from the speaker cable to one of the wires 

from the battery snap (it doesn’t matter which one).

5. Use a Western Union splice to connect the other 

wire from the battery snap to the remaining wire 

coming from the resistor. This completes the 

thermistor circuit, which should resemble Figure 3.

6. Brush a small amount of conductive glue onto 

each of the splices, and allow the glue to dry (or 

solder these splices).

7. Brush liquid electrical tape onto the thermistor 

splices so that all of the bare wires are covered 

(Figure 4).

8. Set your multimeter to measure volts. Set the 

voltage range on your multimeter to at least 

10 volts (check the instructions that came with 

your meter for exactly how to do this). Check the 

voltage of your battery by touching the positive 

lead from the meter to the positive terminal of the 

battery, and the negative lead from the meter to 

the negative terminal of the battery.

9. Connect the 9-volt battery to the battery snap. 

Touch one of the multimeter leads to one wire of 

the resistor, and touch the other multimeter lead 

to the other resistor wire. If the voltage reading 

is negative, reverse the multimeter leads. Your 

Electronic Temperature Sensor is finished!

10. Now you need to calibrate your Electronic 

Temperature Sensor to so that you can use 

voltage measurements to find the temperature 

of the thermistor. Put some ice in one of the glass 

jar (or beaker or plastic cup), and add water so 

that the container is 

almost full. 

Figure 1.

Battery Snap Resistor

Thermistor

Speaker

Wire

Connect Multimeter Leads

at these points to measure voltage

Figure 3.

The Western Union Splice. Bring ends of wires to be spliced together so that the ends are 

pointing in opposite directions (A). Twist each wire 3/4 of a turn in opposite directions (B). 

Turn the ends so they are at right angles to the wires being spliced, and twist each end to 

form at least five more turns spaced as tightly as possible (C). It is easier to make these twists 

with a pair of needle-nose pliers. Cut off the ends and twist them close to the center wire.

A

B

C

A.

B.

C.

Figure 2. Western Union splice.

Figure 4.
oceanservice.noaa.gov 16

11. Put some hot water in the other container, and 

put the thermistor into the water. Wait about 

ten seconds, then measure the voltage as in 

Step 9. Check the temperature of the water with 

the thermometer, and record the voltage and 

temperature in the Calibration Table. 

12. Reduce the temperature of the water from Step 

11 by adding a small amount of cold water. Put 

the thermistor into the water, wait about ten 

seconds, then measure the voltage and check 

the temperature of the water. Record the voltage 

and temperature in the Calibration Table. Repeat 

this step until you have at least eight different 

readings. The highest temperature should be 

around 80° C, and the lowest should be near 0° C.

13. Graph the data from 

the Calibration Table 

with temperature on the 

vertical axis (y-axis) and 

voltage on the horizontal 

axis (x-axis). Now you 

can use this graph to 

find the temperature 

that corresponds to any 

voltage reading from your 

Electronic Temperature 

Sensor.

Want to Do More?

The University Corporation for Atmospheric 

Research Web site has links to interactives, 

simulations, games, and virtual labs about weather 

and climate: https://spark.ucar.edu/interactives and 

https://spark.ucar.edu/activities

Calibration Table

Voltage Temperature

_____ _____

_____ _____

_____ _____

_____ _____

_____ _____

_____ _____

_____ _____

_____ _____

Using Your Temperature Sensor

Your temperature sensor is useful when you want to 

record a series of temperature measurements from the 

same place over a long period of time, and to measure 

temperature in places that can’t be reached with a liquidfilled thermometer. Here are three ideas (you can probably 

think of many more!):

Your Daily Weather

Climate is the average of weather conditions over many 

years, but regular weather measurements are needed to 

calculate this average. Measurements of air temperature 

along with other weather observations help improve 

weather predictions, and also help us understand how 

current weather conditions compare to climate averages. 

To investigate local temperature conditions with your 

temperature sensor, talk with your adult partner to select 

a sheltered location on a north-facing wall, which provides 

some protection from rain and direct sunlight. Install the 

sensor 1.2 to 1.8 m (about 4 to 6 ft) above ground, and 

try to make temperature measurements at the same time 

each day. Record your measurements in a notebook along 

with other observations about the weather at the time the 

measurements were made, such as rain conditions, cloud 

cover, wind, and barometric pressure (see Activity 5, “How 

Do We Know” for more weather instruments). For more 

about weather, climate, and temperature measurements 

and ideas for analyzing your data, see http://globe.gov/

sda/tg/maxmin.pdf.

 Explore a Microclimate

Microclimates are places whose climate is different from 

the surrounding area. They may be very small or as large 

as lakes or cities. Air temperatures over large bodies of 

water can be less extreme than temperatures over nearby 

land areas. Cities are often warmer than surrounding 

areas with fewer humans. Microclimates may also exist 

in valleys, where the bottom of a valley may be much 

colder than the slopes. Smaller microclimates are also 

found in home gardens where buildings, fences, rocks, 

raised beds, paved surfaces, and other features can 

change wind conditions, water flow, and sun exposure. 

Some microclimates are deliberately created to provide 

conditions needed by garden plants, and also to 

improve energy efficiency of buildings. See if you can 

find microclimates near your own home, and use your 

temperature sensor to compare their temperature with 

the temperature of nearby locations. Make daytime and 

nighttime measurements to see whether the microclimate 

effect changes with the time of day. Can you design a 

microclimate that might improve the energy efficiency of 

your home? Try a Web search on “energy efficiency” and 

“microclimate” for some ideas.

Investigate Water Quality

Your temperature sensor makes it easy to measure 

water temperature, and temperature is one of the 

most important characteristics of aquatic ecosystems. 

Temperature affects the biological activity of most 

species, and some species have very specific temperature 

requirements. Water temperature also affects dissolved 

oxygen levels and pH. High water temperatures can 

contribute to outbreaks of bacteria, harmful algae, and 

submerged aquatic vegetation. Talk with your adult 

partner about nearby water bodies that might be 

interesting to investigate. For more information about this 

kind of investigation, see http://archive.senseit.org/files/

Addon_Water_quality_and_temperature.

pdf.

Discover Your Changing World with NOAA