Why the Formation of Ice Doesn’t Cause a Discontinuity in Atmospheric Temperature Lapse Rate: Exploring the Role of Water Vapor

Atmospheric temperature lapse rate refers to the rate at which temperature decreases with altitude in the Earth’s atmosphere. Normally, the temperature decreases at a rate of about 6.5°C per kilometer in the troposphere. However, when ice forms, one might expect the temperature rate to show a discontinuity at the freezing point of water, which is 0°C. However, this is not observed in reality. This article explores the reasons for this phenomenon.

What is the Temperature Lapse Rate?

The temperature lapse rate is a measure of how quickly the temperature of the atmosphere decreases with increasing altitude. It is an important concept in meteorology and atmospheric science because it plays a crucial role in determining the stability and dynamics of the atmosphere.

In the troposphere – the lowest layer of the Earth’s atmosphere where most of our weather occurs – the temperature lapse rate is typically about 6.5°C per kilometer. This means that for every kilometer of altitude increase, the temperature decreases by an average of 6.5°C. However, the actual rate of temperature change can vary depending on a number of factors, such as time of day, season, and location.

Why is there no discontinuity in the rate of temperature change at the freezing point of water?

One might expect that when water freezes and turns to ice, the temperature lapse rate in the atmosphere would show a discontinuity at the freezing point of water (0°C). This is because the freezing process releases a certain amount of heat, known as the latent heat of fusion, which is absorbed by the surrounding air. This would lead to a temporary warming of the air near the surface, potentially interrupting the normal temperature lapse rate.

In reality, however, no such discontinuity is observed. The temperature lapse rate continues to decrease at a relatively constant rate through the freezing point of water, as if nothing had happened. This is because the latent heat of fusion is not enough to significantly change the temperature of the surrounding air. The amount of heat released during the freezing process is relatively small compared to the enormous amount of heat required to warm or cool the entire atmosphere.

The role of water vapor in maintaining the temperature lapse rate

Another reason why the temperature lapse rate does not show a discontinuity at the freezing point of water is the role of water vapor in the atmosphere. Water vapor is a powerful greenhouse gas that absorbs and emits heat in the infrared portion of the electromagnetic spectrum. It plays a critical role in regulating the temperature of the atmosphere.
When water freezes, it releases water vapor into the surrounding air. This water vapor absorbs some of the infrared radiation emitted by the Earth’s surface, which helps maintain the temperature lapse rate. In other words, the water vapor in the atmosphere acts like a blanket, trapping some of the heat and preventing it from escaping into space. This helps to keep the temperature lapse rate relatively constant, even as water freezes and releases latent heat of fusion.

Water vapor also plays a role in the formation of clouds, which can have a significant effect on the temperature lapse rate. Clouds reflect some of the incoming solar radiation back into space, which can cool the Earth’s surface and reduce the temperature lapse rate. However, clouds also absorb some of the outgoing infrared radiation emitted by the Earth’s surface, which can warm the atmosphere and increase the temperature lapse rate.

Conclusion

In summary, the absence of a discontinuity in the atmospheric temperature lapse rate at the freezing point of water is due to a combination of factors. The release of latent heat of fusion during the freezing process is not significant enough to disrupt the normal temperature lapse rate, and the presence of water vapor in the atmosphere helps to maintain a relatively constant temperature lapse rate. Understanding these factors is important for accurately modeling and predicting the behavior of the Earth’s atmosphere, especially in the context of climate change.

FAQs

Q1: What is atmospheric temperature lapse rate?

A1: Atmospheric temperature lapse rate is the rate at which the temperature decreases with altitude in the Earth’s atmosphere.

Q2: What is the normal temperature lapse rate in the troposphere?

A2: The normal temperature lapse rate in the troposphere is around 6.5°C per kilometer.

Q3: Why might one expect a discontinuity in the temperature lapse rate at the freezing point of water?

A3: One might expect a discontinuity in the temperature lapse rate at the freezing point of water because the process of freezing releases a certain amount of heat, known as the latent heat of fusion, which is absorbed by the surrounding air.

Q4: Why is there no discontinuity in the temperature lapse rate at the freezing point of water?

A4: There is no discontinuity in the temperature lapse rate at the freezing point of water because the latent heat of fusion is not enough to significantly alter the temperature of the surrounding air, and water vapor in the atmosphere helps to maintain a relatively constant temperature lapse rate.

Q5: What role does water vapor play in maintaining the temperature lapse rate?

A5: Water vapor plays a critical role in maintaining the temperature lapse rate by absorbing and emitting heat in the infrared part ofthe electromagnetic spectrum, and by releasing water vapor into the surrounding air as water freezes, which helps to maintain a relatively constant temperature lapse rate.

Q6: How do clouds impact the temperature lapse rate?

A6: Clouds can impact the temperature lapse rate by reflecting some of the incoming solar radiation back into space, which can cool the Earth’s surface and lower the temperature lapse rate. However, clouds also absorb some of the outgoing infrared radiation emitted by the Earth’s surface, which can warm the atmosphere and increase the temperature lapse rate.

Q7: Why is it important to understand the absence of a discontinuity in the temperature lapse rate at the freezing point of water?

A7: Understanding the absence of a discontinuity in the temperature lapse rate at the freezing point of water is important for accurately modeling and predicting the behavior of the Earth’s atmosphere, particularly in the context of climate change.