All About Weather for Middle School Science

2 days ago

4 min read

Clouds are an important part of the water cycle. Clouds are how liquid water moves through the atmosphere. This blog post will teach you all about how clouds form, the different types of clouds, and how clouds affect the Earth.

If you would like a copy of the picture book, you can get it along with the reading passage, flashcards, and comprehension activities at Teachers Pay Teachers.

Weather

What is Weather?

Weather is the temporary condition of the atmosphere in a specific area. Climate is the average weather of an area over a long period of time.

The atmosphere is all of the gases that surround Earth. It is made up of layers with different properties. The layer closest to the Earth is called the troposphere. Almost all weather happens in the troposphere, but occasionally weather can stretch into the stratosphere, the layer above the troposphere.

Weather is made up of six parts: temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness. These parts combine to describe the weather in a location.

Temperature

Temperature is a measure of how hot or cold an area is. We measure temperature using a thermometer. Gabriel Fahrenheit invented the first mercury thermometer in 1714. A mercury thermometer measures temperature using rising and falling mercury in a tube. Fahrenheit divided the space on his mercury thermometer between freezing and boiling water into 180 degrees. He set the freezing point at 32 degrees so that he didn't need to use negative numbers to measure the coldest ice water he could create in his lab. Outside, however, temperatures do reach negative numbers. The coldest temperature recorded on Earth was -128.6 degrees Fahrenheit on July 21, 1983, in Antarctica.

While we still use the Fahrenheit system in the United States, the rest of the world uses Celsius to measure temperature. In 1742, Anders Celsius divided the space between freezing and boiling water into 100 degrees. Water freezes at 0 degrees Celsius and boils at 100 degrees Celsius. The hottest temperature recorded on Earth was 56.7 degrees Celsius, or 134.1 degrees Fahrenheit, on July 10, 1912, in Death Valley, California.

In the troposphere, the air gets colder as elevation increases, so the top of a mountain is colder than the valley below it. One of the reasons Death Valley is so hot is that it is 190 feet below sea level. Air temperature also changes based on latitude. Sunlight hits the equator more directly than the poles, so the air around the equator is warmer than the air at the poles.

Atmospheric Pressure

Atmospheric pressure is the weight of the atmosphere above us. Meteorologists measure atmospheric pressure in atmospheres, millibars, and inches of mercury. One atmosphere is equal to 1013.25 millibars or 29.9 inches of mercury A barometer is a tool used to measure atmospheric pressure. It records measurements in millibars or inches of mercury.

The atmospheric pressure is higher at lower elevations than higher elevations because more of the atmosphere is above the surface. At sea level, the atmospheric pressure is equal to 1 atmosphere. At the top of Mount Kilimanjaro in Tanzania, the atmospheric pressure is 0.4 atmospheres.

Atmospheric pressure also changes depending on the temperature of the air. Warm air rises, so atmospheric pressure in warm areas is low because there are fewer air molecules near the surface of the Earth. Low-pressure areas are usually warmer with storms and rain. Cold air falls, so atmospheric pressure in cold areas is high because there are more air molecules near the surface of the Earth. High-pressure areas are usually cooler with clear skies.

Wind

Wind is the movement of air. Air moves due to differences in pressure. Air molecules move from colder high-pressure areas to warmer low-pressure areas. When warm air rises, fewer air molecules are left near the surface of the Earth. Colder air molecules rush in to fill the space left behind by the rising warm air molecules. The higher the pressure difference between two areas, the faster the wind blows.

There are both local and global winds. Local winds are the winds caused by the geography of the area, including bodies of water and mountains. These winds move from areas of high pressure to areas of low pressure in a relatively straight line.

Global winds are much larger and caused by the uneven heating of the Earth and the Earth's rotation. As warm air heated by the Sun at the equator rises, cold air from the poles rushes to fill its place. These winds do not move in a straight line; they curve based on the spin of the Earth. The equator spins faster than the poles, so as air from the north pole moves south, it deflects to the left. As the air from the south pole moves north, it veers to the right. The way the speed of the Earth's rotation changes the direction of moving wind and water is called the Coriolis Effect.

The fastest winds on Earth happen during tornadoes. In a tornado, air spins around a low-pressure center. In 1999, the strongest tornado winds ever were recorded during the Bridge Creek-Moore tornado near Oklahoma City. During the storm, meteorologists measured wind speeds of about 300 miles per hour. Hurricanes also have strong winds, but the highest windspeeds recorded during a hurricane were only 190 miles per hour.

More Weather Resources

Are you looking for weather resources for younger students? My team at For the Love has a fantastic presentation for teaching about weather in elementary school. You can get the presentation at Teachers Pay Teachers.