Definition of Ambient temperature: It is a commonly used term whenever people are talking about applications which involve heat transfer of any kind. Ambient temperature refers to the temperature of the environment or in more precise terms it denotes the temperature of the area surrounding a particular system which is under discussion. Ambience means surrounding so ambient temperature is the temperature of surrounding.
Example of a Room & House: For example if we are inside a room, and the room is our system then the surrounding of room’ temperature is the ambient temperature for us. The temperature inside the room which may be cooled by an air conditioner is the temperature of our system under consideration. But when we step outside the room and our system is changed to for example the entrance in a house then the ambient temperature becomes whatever value is outside the entrance of the house which is normally higher than room temperature in summer and lower in winter.
Applications & Significance: Ambient temperature is a very important consideration during the design of temperature controlled environments or heating & cooling systems. These include air conditioners, refrigerators, air cooled engines and server farms. Machinery and equipment usually dissipate the heat they produce into the environment to avoid component damage due to over heating. Since the heat transfer depends upon the temperature difference between two objects, a larger difference would mean more heat transfer. This means that the machinery will lose more heat and perform better in a cool environment than a hot one. Another example would be cooking food in an oven. When talking about the food, the ambient temperature would be the temperature inside the oven.
Confusion Related to Ambient temperature: It is sometimes also confused with room temperature which is different since room temperature is used when discussing the temperature inside a temperature controlled building and is usually considered to be 25 degree Celcius. Ambient temperature however refers to the temperature of the surrounding of the object in consideration.