Which of the following statements is true about changes to the humidity of air over time?

The humidity of air can increase, and it can decrease.

The humidity of air can increase, but it cannot decrease.

The humidity of air cannot change.

The humidity of air can decrease, but it cannot increase.

Can warm water increase the temperature of the air above it?

Yes, the temperature of the water can affect the temperature of the air even if the water is only a little bit warmer than the air.

It depends on how warm the water is because the temperature of the water can affect the temperature of the air only if the water is much warmer than the air.

No, the temperature of the water cannot affect the temperature of the air because the temperature of air cannot change.

No, even though the temperature of air can change, warm water cannot increase the temperature of the air above it.

Cool air is blowing from Location 1 toward Location 2, where the air is warmer. When the air that was at Location 1 reaches Location 2, clouds begin to appear. If there is no increase in the amount of water vapor in the air as it moves, what could explain why the clouds appear in the air at Location 2?

The cool air pushed the warm air upward, which caused the warm air to cool, condense, and form clouds.

The clouds must have moved from somewhere else because air without clouds cannot turn into air with clouds.

The warm air pushed the cool air upward, which caused the cool air to become warmer, condense, and form clouds.

The cool air pushed the warm air upward, which caused the warm air to become warmer, condense, and form clouds.

Which of the following statements is true about rain falling from clouds?

The tiny droplets of liquid water that make up clouds combine into larger droplets, and those droplets fall as rain.

Clouds are not made of liquid water but they hold liquid water, and wind releases this water as rain.

Rain does not fall from clouds. It just falls from the sky.

Clouds are not made of liquid water but they hold liquid water, and when the pool of liquid water that fills the inside of clouds gets too large for the cloud to hold, the cloud releases the water as rain.

In the diagram, warm air is moving over a lake and upward along the side of a mountain. Where in this diagram are clouds more likely to form: over the lake or over the mountain?

Over the mountain because air can become cooler as it moves up the side of a mountain, and clouds often form as air cools.

Clouds do not form in air that does not already have clouds. For it to be cloudy somewhere, existing clouds must move to that place from somewhere else.

Over the lake because the lake is a source of water vapor for the moving air, and clouds always form close to where water evaporates.

Over the mountain because clouds often form on mountains, not because the air is cooler on the mountain.

If the temperature of the air in a town is cool, and the town has no rivers or lakes and is not close to an ocean, could the air at that town have water vapor in it?

Yes, the air at that town could have water vapor in it because the water vapor can come from water in plants or soil even when the air is cool.

No, the air at the town does not have to be warm, but it must be close to a large body of water to have water vapor in it.

No, the air at the town does not have to be close to a large body of water, but it must be warm to have water vapor in it.

No, the air at the town must be both warm and be close to a large body of water for the air to have water vapor in it.

Does energy from the sun increase the temperature of the surface of the earth?

Energy from the sun increases the temperature of both the land and the water.

Energy from the sun increases the temperature of the water, but it does not increase the temperature of the land.

Energy from the sun increases the temperature of the land, but it does not increase the temperature of the water.

Energy from the sun does not increase the temperature of the land or the water.

A girl who often plays with her friends in front of her house notices that the concrete sidewalk tends to be much warmer in the middle of day in the summer than it is in the middle of the day in the winter. Other than the ground and air being colder in the winter, what else explains why the sidewalk is colder in the winter than in the summer?

The angle at which sunlight reaches the concrete in the middle of the day is smaller in the winter, so sunlight transfers less energy to the concrete during the winter and does not warm the concrete as much as it does in the summer.

The amount of energy that sunlight transfers to the concrete does not change throughout the year. The only way the concrete could be colder in the winter than in the summer is if more clouds blocked the sunlight so the sunlight could not warm the concrete as much as it does in the summer.

The sun is cooler in the winter, so sunlight transfers less energy to the concrete in the middle of the day in the winter and does not warm the concrete as much as it does in the summer.

The sun is farther from the earth in the winter, so less energy from sunlight reaches the concrete in the middle of the day in the winter and does not warm the concrete as much as it does in the summer.