Investigate Our Climate & Weather

Investigate Alabama’s Weather

The weather station in your outdoor classroom includes various weather instruments that you can use to measure, record and track weather conditions over time.

Observing the clouds overhead can help you understand and predict weather.

Investigate
Alabama’s Weather

The weather station in your outdoor classroom includes various weather instruments that you can use to measure, record and track weather conditions over time.

Observing the clouds overhead can help you understand and predict weather.

Riverton Elementary Weather Station

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Alabama's Climate

What is the difference between climate and weather?

Are weather and climate the same thing? No. There is one big difference between the two – time!

Weather is short-term and climate is long-term. Weather reflects changes in the atmosphere in a certain area – air pressure, temperature, humidity, wind speed and direction, and lots of other things. This can change by the minute, hour, or day.

Climate reflects averages of precipitation, temperature, humidity, sunshine, wind, and other measures of weather that occur over a long period in a particular place.

Dreamstime

Alabama’s climate is warm and humid and is characterized by relatively mild winters, hot summers, and year-round precipitation. We owe this to our close proximity to the equator, tropical systems (like hurricanes), and the warm waters of the Gulf of Mexico.

Alabama's Weather Patterns

Seasons in Alabama:

Because of Earth’s orbit around the sun and its tilt, we experience variations in day length and temperature patterns throughout the year. This, as well as large air masses moving over the continent, gives us seasons!

In summer, a large mass of warm, moist air (a maritime air mass) moves northward from the Gulf of Mexico into the state. This gives us our warm, humid summers.

In fall, cool, dry air (a Continental Polar air mass) moves southward into the state. These cold fronts force the warm, moist air upward into the atmosphere, causing rain showers or even snow. Once the rain or snow clears, we typically experience several days of cool, sunny weather until the next cold front comes in. The cool Continental Polar air masses typically stop moving southward around March (the end of winter and start of spring) and the warm maritime air masses dominate our weather once more.

Earth’s Tilt
Wikimedia – Saperaud

Day Length:

The shortest length of day that we experience is in late December. We call this the Winter Solstice. In Alabama, we get 10 hours of daylight.

The longest length of day that we experience is in late June. This is the Summer Solstice. In Alabama, we get 14 hours of daylight.

Dreamstime

Temperature:

Average temperatures are slightly higher in the southern half of the state then in the northern half of the state. For example, take the average minimum daily temperature in the coldest month versus the hottest month across the state.

	Average minimum daily temperature (°F) in January	Average maximum daily temperature (°F) in July
Mobile County (South)	39.9	91.2
Montgomery County (Central)	35.8	93
Madison County (North)	29.3	86.5

You’ll notice that average maximum daily temps in Montgomery County are higher than in Mobile County, which is farther south. This is because Mobile County is coastal and is influenced by the Maritime Effect. The Gulf of Mexico’s airflow impacts the climate of the areas nearby, causing milder temperatures and less variation in temperature.

Alabama’s record breaking temperatures:

Highest recorded temp in AL: 112°F at Centreville, Bibb County, on September 5, 1925
Lowest recorded temp in AL: -27°F at New Market, Madison County, on January 30, 1966

Precipitation:

The northern half of the state also has higher average levels of precipitation than the southern half.

	Average Annual Precipitation (inches)
Mobile County (South)	57
Montgomery County (Central)	53.1
Madison County (North)	65.9

Weather Instruments

Your weather station should have a cardinal direction sign as well as some or all of the weather instruments listed below.

Cardinal Direction Sign:

The cardinal direction sign is used to remind you which direction is North, South, East, and West. This is helpful when studying wind patterns in particular.

Thermometers:

Thermometers measure the air temperature. When air around the tube of liquid (such as alcohol or mercury) changes temperature, the liquid expands and moves up the tube. A scale then shows what the actual temperature is.

Thermometer

Anemometers:

Anemometers measure wind speed. Cups attached to horizontal bars catch the wind. Those bars are all attached to a single vertical rod that rotates as the cups catch wind. The anemometer counts the number of rotations of the vertical rod and determines the wind speed.

Because wind isn’t constant, but rather in gusts and lulls, wind speed is actually determined by the average recorded speed over a short period of time.

Anemometer

Hygrometers:

Hygrometers measure humidity,(amount of water vapor) in the air. It is measured as a percentage of how much water is in the air at a given time versus how much water vapor the air can hold at maximum.

At one hundred percent, the water vapor will condense back into liquid water and become rain.

Hygrometer

Rain Gauges:

Rain gauges measure the amount of rain that has fallen over a specific time period. The measuring tube catches rainfall and must be emptied out between recordings for accuracy.

Rain Gauge

Barometers:

Barometers measure air pressure in the atmosphere, also called barometric pressure. The layers of air around Earth make up our atmosphere. The air has a weight and presses against everything it touches, including a barometer. The barometer reads pressure changes which allows meteorologists to predict short-term weather changes. If the pressure drops, you can expect wind, clouds, and rain. If pressure increases, you can expect clear skies and cool, dry air.

Wind Sock:

A wind sock is a cone-shaped tube of fabric, which resembles a giant sock, attached to pole that rotates. It helps us determine wind direction and relative wind speed. When wind blows, it fills the sock. Use the cardinal directions sign in your outdoor classroom along with your wind sock to determine the direction the wind is blowing.

Wind Sock

Clouds

What are clouds?

Clouds are actually just collections of very tiny droplets of water or ice crystals. When warm air rises, it expands and cools. Warm air is able to hold more water vapor than cool air. Once the air has reached its maximum amount of water vapor it can hold, the vapor turns into a liquid form (rain) or solid form (ice).

What makes them white or gray?

As light from the sun moves through the clouds, it is scattered by the water droplets or ice crystals in the cloud. Thin clouds let more light through and appear white because the water droplets or ice crystals are large enough to scatter the light into all seven wavelengths (red, orange, yellow, green, blue, indigo, and violet) – combining to produce white light.

When the number of water droplets or ice crystals gets too high or they get loo large, less and less sunlight makes it through the cloud. This causes the cloud to appear darker. Storm clouds can appear black because there is no light making it through, so you’re basically just seeing a shadow of the collection of water droplets or ice crystals.

Types of Clouds

There are many different types of clouds. They are grouped by their height in the sky as well as their appearance. They can be good indicators of what weather is to come within the next day or so. Below is an illustration (source: wikimedia – Valentin de Bruyn) as well as a chart with descriptions of the most common cloud types.

(source: wikimedia – Valentin de Bruyn)

Cirrus:

High height: above 18,000 feet
Most common of the high clouds
Thin, whispy, made of ice
Looks like a cotton ball pulled apart and stretched out
Predict: If there are only a few of these clouds in the sky, the weather will be fair for now. Increased coverage, however, indicates a change of weather will occur within the next 24 hours.

Cirrus Clouds
Wikimedia – Simon A. Eugster

Cirrostratus:

High height: above 18,000 feet
Thin, sheet-like
Often cover the entire sky
Sun and moon can be seen through them
Predict: Normally come between 12-24 hours before rain or snow.

Cirrostratus Clouds
Flickr – Gexydaf

Cirrocumulus:

High height: above 18,000 feet
Small, rounded white puffs that appear in long rows
Can resemble the scales of a fish
Predict: Typically seen in winter and indicate fair weather. In tropical regions, they can indicate an approaching hurricane

Cirrocumulus Clouds
Wikimedia – Simon Eugster

Altostratus:

Medium height: 6,500 – 18,000 feet
Similar to stratus, but higher in the sky
Gray or blue-gray
Typically cover the whole sky
In thinner areas of the cloud, the sun may be dimly visible as a simple round disc
Predict: These clouds usually form ahead of storms with continuous, light rain or snow.

Altostratus Clouds
Wikimedia – The Great Cloudwatcher

Altocumulus:

Middle height: 6,500 – 18,000 feet
Puffy gray masses (like cumulus but higher in the sky)
Form in groups
Predict: Typically these indicate that a storm has just passed and fair weather is here. If the weather has been mild, it’s likely that these clouds are buliding and will bring rain or snow.

Altocumulus Clouds
Wikimedia – farmartin

Stratus:

Low height: Up to 6,500 feet
Uniformly gray; cover the entire sky
Also called “overcast”
If their bases reach the ground, they become fog.
Bring light mist or drizzle
Predict: Typically these clouds mean the atmostphere is stable and not much is going to happen. If they are thick and hanging around, expect light rain or snow. Also expect cooler temperatures to come.

Stratus Clouds
Wikimedia – The Great Cloudwatcher

Stratocumulus:

Low height: Up to 6,500 feet
Puffy and gray
Form in rows with blue skies visible between them
Predict: They indicate that a change in weather is coming. Precipitation is rare, but they can turn into nimbostratus clouds.

Stratocumulus Clouds
Flickr – J.N. Stuart

Nimbostratus:

Low height: Up to 6,500 feet
Dark gray cloudy layer
Blanket-like
Predict: These clouds bring continuously falling rain or snow. Can last several hours to days. When the clouds start to break, expect colder temperatures.

Nimbostratus Clouds
Wikimedia

Cumulus:

Also called “clumping clouds”
Height: can span across low, middle, and high layers
White and puffy
Looks like floating cotton
Base of each cloud is flat, and the top has rounded towers
Predict: When they are small and wispy they are a sign of fair weather. When the tops look like heads of cauliflower, they can grow into cumulonimbus clouds which bring storms.

Cumulus Clouds
Wikimedia – PiccoloNamek

Cumulonimbus:

Height: can span across low, middle, and high layers
From far away they look like big mountains or towers
Wind flattens the top of the cloud into an anvil shape
Cumulonimbus clouds grow on hot days when warm, wet air rises very high into the sky. From far away, they look like huge mountains or towers.
Predict: These clouds can produce short-lived severe storms, heavy rain, intense lightning, hail, and even tornadoes. They drop a large amount of precipitation but it doesn’t last long. The day may begin sunny, followed by a heavy rain and storm, and then an afternoon of sun once again.